When I create a patch queue for an existing repository, there are two places where Bb offers the option to apply a patch: one on the Patch Series tab, and one on the Source tab (next to the patch name).
The former reports "patched" after I click on it, but appears to do nothing else. The latter reports an exception. Neither one actually applies the patch to the original repository (I may be misunderstanding the intent of this feature, so the solution to this ticket may just involve some docs). In both cases, the next time I visit the controls, the option to patch is still there.