Hello Colin,
Thank you for the provided screenshot.
I have been looking into your question and I created a small sample trying to reproduce the described behavior. On my side everything works as expected and I am able to switch between tabs during both design and run-time and the controls for every UltraTabPage are properly displayed.
I would like to add that this behavior is possibly related to your other query from this forum thread. I would suggest upgrading your project to a single version before proceeding with resolving the current issue.
Attached you will find my sample for your reference. Please test it on your side and let me know how it behaves. If this is not an accurate demonstration of what you are trying to achieve please feel free to modify it and send it back to me along with steps to reproduce. Alternatively, if the behavior cannot be replicated please feel free to provide your own sample. Remove any external dependencies and code that is not directly related to the issue, zip your application and attach in in this case.
Having a working sample on my side, which I can debug, is going to be very helpful in finding the root cause of this behavior.
Thank you for your cooperation.
Looking forward to hearing from you.
Regards,Bozhidara PachilovaAssociate Software Developer