Comment 3 for bug 311040

Okay, I've traced it down to these lines in panda/src/glstuff/glGraphicsBuffer_src.cxx :
        if (get_rtm_mode(i) != RTM_bind_or_copy) {
          continue;
        }
Uncomment them to make it work. For some reason, it doesn't want to do anything when the mode isn't RTM_bind_or_copy.
I don't have a clue what RTM_bind_or_copy is, I gotta check that before I can safely disable this.