Bug Report:

Whenever the foreign key column of the grid is configured for multi checkbox filtering and is nullable, the value of the "null" option is sent to the server as "NaN".

Steps to replicate:

1. Set ForeignKey column

2. Make the column nullable

3. Set the filterable.multi option to true

4. filter by the null value

A sample project with reproduction has been shared in Ticket with ID: 1463089

### Bug report


### Reproduction of the problem
On the mobile version on Android 10, the Grid does not enter incell editing.

Dojo to reproduce: https://dojo.telerik.com/oDUBuKAt


### Environment

* **Kendo UI version:** 2020.1.219
* **Browser:** Android 10 Web Browser 

Bug report

When the data source of the grid is set to WebAPI, the Batch option is not available. 

Reproduction of the problem

1. Set the DataSource to WebAPI()

2. Attempt to enable the Batch(true) option.

Description

Reproducible only with the latest version of the suite - 2019.3.1023. The Batch option is available in the 2019.3.917 version.

Environment

* **Kendo UI version:** 2019.3.1023
* **jQuery version:** 1.12.4
* **Browser:** [all] 

Bug report

The Kendo UI Sortable for ASP.NET Core assumes that all selectors are by "id".

Reproduction of the problem

1. Set the .For() option of the Sortable widget to a class selector:

@(Html.Kendo().Sortable()
    .For(".k-grid table")
    // . . . 
)

2. Inspect the page source.

3. The following string is rendered:

<script>
    kendo.syncReady(function () { jQuery("\\.k-grid table").kendoSortable(// options) });
</script>

Expected/desired behavior

The Sortable widget should allow for passing any jQuery selectors.

Environment

* **Kendo UI version:** 2019.3.1023
* **jQuery version:** 1.12.4
* **Browser:** [all] 

Hi Kendo Team,

I am working on Kendo UI ASP.NET Core Grid binding with SignalR. But while starting Hub and providing the Promise, I am facing an error "The "promise" option must be a Promise."

I am following this URL for reference: https://demos.telerik.com/aspnet-core/grid/signalr .

Checked on your website as well, but the issue is also coming there. Here is the URL: https://docs.telerik.com/kendo-ui/api/javascript/data/datasource/configuration/transport.signalr

In this link, when clicking on "Open In Dojo" button, it opens a new window, then clicks on the Run button. It will generate an error in the console "Uncaught Error: The "promise" option must be a Promise.". 

Please check the attached snapshot.

Please reply asap. Thanks in advance!