When tabbing in grouped RadGridView placed in Grid with another visual element inside it, GroupRenderMode is set to Flat  and second group is not in ViewPort, selected row changed its state to Unfocused.

Application hangs on start up if GroupRenderMode is set to Nested, there is a column with Width Star and a group descriptor applied.

The workaround could be using QueryableCollectionView instead. Still, it does not suggest the exact same functionality as ICollectionView.

When a gridview is placed in TabControl, the following CodedUI tests will fail:

Test 1. Click on a column header to sort by that column.

Test 2. Click on a drop-down button to filter a column.

Test 3. Drag a column to group by it. 

GridViewDataColumn doesn't respect FallbackValue when the source property returns DependencyProperty.UnsetValue

The same works fine with the old Nested mode.

When TabStopMode is set to "Skip" on all columns and you press Tab, RadGridView scrolls a little.

Workaround: define a custom KeyboardCommandProvider and clear the pending commands.