Hi, I have had the same problem, but solved it by installing some cb-plugins new.
A reversion of the tab access didn't work, because they have been comletely lost.
In my case the article-tab and the uddeim-inbox-tab were affected.
When I installed the new version of uddeim 2.5 beta with related cb-plugins they suddenly reemerged together with the restricted access levels set before.
May be its a bug of uddeim 2.4 beta in combination with custom user-groups in J1.6?
Hope, any update like this will work for you, too.