Steps to reproduce the problem:

Using the Default or Material Kendo Theme (v5.6.0) with the Telerik HTML5 Report Viewer, the Boolean parameter which uses a Checkbox for it's display, is not visible (this may affect other themes as well).

I confirmed an older version v4.40.0 has a height and width set for the k-checkbox CSS class as such:

https://unpkg.com/@progress/kendo-theme-material@4.40.0/dist/all.css

.k-checkbox {
    border-radius: 2px;
    margin: 0;
    padding: 0;
    width: 16px;
    height: 16px;
    line-height: initial;
    border-width: 2px;
    border-style: solid;
    outline: 0;
    box-sizing: border-box;
    background-position: center;
    background-repeat: no-repeat;
    background-size: contain;
    display: inline-block;
    vertical-align: middle;
    position: relative;
    cursor: pointer;
    -webkit-appearance: none;
}

while the latest v5.6.0 does not:

https://unpkg.com/@progress/kendo-theme-material@5.6.0/dist/all.css

.k-checkbox {
    margin: 0;
    padding: 0;
    line-height: initial;
    border-width: 2px;
    border-style: solid;
    outline: 0;
    background-position: center;
    background-repeat: no-repeat;
    background-size: contain;
    display: inline-block;
    flex: none;
    vertical-align: middle;
    position: relative;
    cursor: pointer;
    -webkit-appearance: none;
}

The checkbox is actually on the page, but is so small it's basically invisible and completely unusable, requiring a manual CSS override to fix.

When exporting to PDF from Telerik Report Designer the software creates a list of flat links for each TOC entry, but the links are separated in the structure from the TOC Label. While a good start, it would be better to use a main TOC tag under which each line in the TOC would receive a TOCI (Table of Contents Item) tag. Each TOCI would contain the label and link for the respective item. Attaching a few examples to assist.

References:

https://www.hhs.gov/sites/default/files/pdf-tagging.pdf (page 29).

https://www.pdflib.com/pdf-knowledge-base/pdfua/the-pdfua-standard/ 

When exporting the tags for the document's Table of Contents Telerik Report Designer exports TOC leaders as distinct tags, requiring that they be removed when completing the accessibility tagging for the document. Leaders - the ellipses found in the Table of Contents (e.g., Introduction ...................... Page 3) between the TOC item and the page number will be read by assistive technology as "dot dot dot dot dot..." etc. They need to be deleted from the tag tree. Please Artifact them or (preferably) NOT tag them on the export. Thanks.

Reference: 

https://www.levelaccess.com/pdf-table-of-contents/

https://www.w3.org/TR/2014/NOTE-WCAG20-TECHS-20140408/pdf.html 

Ideally, if the user prints a report, the output should be the same as what they see on the screen.

Currently, if the user prints/exports the report sometime after previewing it, the data will be updated and they will not get what they see.

The following Base64 image:

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

is recognized by the Reporting engine as SVG, which results in the following error in the PictureBox:

An exception has occurred while processing 'pictureBox1' item:
System.Xml.XmlException: The '�' character, hexadecimal value 0xFFFD, cannot be included in a name. Line 1, position 5.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.ParseElement()
   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
   at System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace)
   at System.Xml.XmlDocument.Load(XmlReader reader)
   at System.Xml.XmlDocument.LoadXml(String xml)
   at Telerik.Reporting.Svg.RadSvgImage.SvgDocumentFromXml(String xml)
   at Telerik.Reporting.Processing.Imaging.SvgImageItem.CreateImageInfo()
   at Telerik.Reporting.Processing.Imaging.IImageInfoMapExtensions.StoreImageData(IImageInfoMap imageInfoMap, IImageItem imageItem, ICache cache)
   at Telerik.Reporting.Processing.PictureBox.ResolveImage(Object value)
   at Telerik.Reporting.Processing.PictureBox.ProcessItem()
   at Telerik.Reporting.Processing.ReportItemBase.ProcessElement()
   at Telerik.Reporting.Processing.ProcessingElement.Process(IDataMember dataContext)

As explained in this support ticket (https://www.telerik.com/forums/specify-default-print-settings---number-of-copies), our customers want to be able to set the default value of the number of copies for a report since they require multiple copies for their business processes.

Would it be possible to enable setting the default values for the printing when a report is generated?

When a TRDP/TRDX report is imported to a CS report, the produced .designer.cs does not have Unicode encoding, instead, it is with ANSI encoding.

Because of this, some of the report text might instead be displayed as ????

The workaround is to Save As the file, from Visual Studio, with Encoding which will open a window where you may change the encoding to Unicode.

I have a multipage report and my Html5 Viewer is set up in an ASP.NET Core application in .NET 5. The viewer's settings are:

viewMode: "PRINT_PREVIEW",
scaleMode: "FIT_PAGE_WIDTH",
pageMode: "CONTINUOUS_SCROLL",

The problem is that I cannot scroll down to the end of the report.

The issue may not occur in other frameworks with the same report.

in the new/current Version "16.2.22.914", when dragging an DataSource-Field on the Report, the resolved expression is wrong.

In the previous Version "16.2.22.622", this worked as expected, see Screenshot.

The attached report demonstrates the issue.

Currently a single instance of the WPF Report Viewer will often use multiple different HttpClient instances to talk to the Report Server.  This means that cookies added as part of earlier requests may not be sent in later requests.  If the Report Server is behind a load balancer that uses cookies to implement 'sticky sessions', this loose behavior with cookies will cause requests to get routed to different servers which is not ideal.  It is possible to use a storage mechanism on the server that natively supports a web farm (such as the Redis storage option) but that can be tricky to set up.  

Instead, if the report viewer were to re-use the same HttpClient instance for all requests (including initial render request, export requests, print requests, etc.), the load balancer could work to route all requests to the same web server and then any storage mechanism (such as the simple File storage option) would work.

This issue was reported back in 2017 and I'm running into the problem again in 2022.  See: https://www.telerik.com/forums/wpf-reportviewer-cookie-behavior

On the last step of the SqlDataSource Wizard in the Web Report Designer, executing the query to preview the records displays the columns with a lowercase character at the beginning which can be confusing.

After the wizard, the names of the columns are correct and can be used as expected by the designer.

Currently, the fields' names are case-sensitive for those 2 data sources while other data sources, like the CSV for example, will ignore the casing.

For example, if there is a JsonDataSource with a Column1 field, it has to be written exactly as is in the expression while in the CsvDataSource, the field will be resolved even when written like Fields.column1 in an expression.

In the Web Designer, I can create OhlcSeries but I cannot find a way to provide the OHLC marks. Whatever I enter for Y value, in the Design view I see the error "The XML serializer cannot resolve type with name: Telerik.Reporting.OhlcMarks". In Preview the error is "An error has occurred while processing Graph 'graph1':ohlcSeries1: OHLC values value cannot be null or empty when using NumericalScale".
If I created an OHLC chart with the Standalone Designer and opened it in the Web Designer, the Y value would display "[object Object]" as seen in the linked screenshot.

Add the "Not In" operator for the Filter rules - Filter Rules - Telerik Reporting.