Sorry for not following up on your additional comments earlier. I am in the process of getting an environment set up, where I can test our VSExtensions' compatibility with Oxygene.
The Wpf VSExtensions are check if appropriate (wpf) projects are present each time you load a solution.
I have reviewed the code in the stack trace you sent earlier and all
exceptions are handled in that specific portion of our code. Another peculiar thing is the fact the code for the stack trace you sent is used in all of our VS Extensions, whereas the issue you are experiencing is only related to the Wpf ones (looking through your download history, I am assuming you use other Telerik products as well).
I will get back to you with my findings as soon as I'm done testing with Oxygene.
All the best,
the Telerik team