I am not exactly sure what the issue is here, but I was testing a similar problem for a client and found what appears to be a work-around / solution.
Backup the application first...
Open the app in v11 SR1 desktop
Add some new tabs and position them at the front of the tab row,
Use Copy All and Paste to replicate the content on your old tabs onto the new tabs
Delete the old tabs and re-label the new ones
Save to the server and test in AJAX. Problem should hopefully be solved.