So I am uncertain if this bug was around before, but in 0.96 (the latest opt-in version) it is present.
Aside from the first module, namely the cultural forum, I am unable to upgrade my cultural starbases after I unlocked the modules through techs.
I unlocked multiple of the techs that should allow you to build these modules, but none of them show up on upgrade screen.
Honostly this annoyed me pretty hard, since I wanted to play a peacefull game for a change, and now i threw out 6 hours of my day-off because the game is near launch and still riddled with basic bugs.
Sigh.....
Edit: updated version number