Could you confirm that the workaround suggested by Tina with removing the the IsTabStop property does not work. I just checked and the forward and backward tab navigation worked as she described it.
As for the PITS issue, we migrated to a newer feedback portal and I believe the issue you referred to is this one
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items