When the value contains a semicolon the HTML style property values are omitted on import:

<th width ='12%;' ...>

Currently, setting it without semicolon imports the value successfully:

<th width ='12%' ...>

 Tables should ignore fixed proffered width with the value of 0, this is the default behavior in Word as well.

Workaround (when converting Flow to PDF documents): 

foreach (var item in tables)
{
    if (item.PreferredWidth.Type == Telerik.Windows.Documents.Flow.Model.Styles.TableWidthUnitType.Fixed && 
        item.PreferredWidth.Value == 0)
    {
        item.PreferredWidth = new Telerik.Windows.Documents.Flow.Model.Styles.TableWidthUnit(Telerik.Windows.Documents.Flow.Model.Styles.TableWidthUnitType.Percent, 100);
    } 
  
    
}

At this point, only background-color is supported. Add support for bgcolor attribute as well. It could be used with the following tags: body, marquee, table, tBody, td, tFoot, th, tHead, tr.

There are 27 types of border styles in the Open XML specification and they are implemented in RadFlowDocument. Part of the borders are already supported (eg. None, Single, Dotted) when exporting to HTML, all others are treated as None and stripped.

The HTML format doesn't support all types of border styles OOXML format supports.

Such objects are defined as oleObject elements in the XML:

<w:object w:dxaOrig="3795" w:dyaOrig="3555">
	<v:shape id="_x0000_i1026" type="#_x0000_t75" style="width:32.85pt;height:30.55pt" o:ole="" fillcolor="window">
	  <v:imagedata r:id="rId9" o:title=""/>
	</v:shape>
	<o:OLEObject Type="Embed" ProgID="PBrush" ShapeID="_x0000_i1026" DrawAspect="Content" ObjectID="_1647182330" r:id="rId10"/>
</w:object>

Currently, they are skipped on import.

Wrongly imported/exported table cells from nested tables (see the picture below).