Closed Unassigned: TabContainer hidden on 15.1 [27805]

So i have a mix between ajax control toolkit and rad control toolkit which was working just fine.

Now TabContainer is not displaying when one or more tabs have inside a RadGrid component.

Once i inspect the html, i got TabContainer with visibility : hidden.
It's probably a render issue between those two.

I have performed various tests but with no luck, even an empty radgrid cause the problem.

Any other components are working.

This only happens after i upgrade my ajax control toolkit to 15.1

Update1: I can't upload a sample project since i can only upload 4mb