Indesign Updates and Extension panels not rendering

Hi everybody !
Blank extension panels have been discussed thousand times before, but i can't work this one out.
We updated Indesign yesterday on 2 iMac, since then my 3 homemade extensions don't render in their panels. Well, to be acurate :
3 extensions didn't render on my own computer (which contain dev versions for each extension, plus an extension installed via Anastasiy's ExtensionManager, hence existing at 2 locations : dev and prod). Player Debug Mode is 1 for CSXS 8 and 9.
On the second computer,
2 extensions had prod versions installed, and the last one was dev version. THough on THIS computer, ONE of the 2 prod extensions was still working.

We then tried to remove dev versions on my computer, installed prod versions. I tried changes in the manifest. I tried resetting of prefs/cache files. Nothing got the job done.

Finally we installed previous Indesign versions one after the other until extensions worked again.

BUT things couldn't stay at this point, the story needed a little more – if not chaos – let's say magic. My coworker couldn't help herself from getting back to up-to-date Indesign Version (16.3.2). And guess what, the 2 extensions installed in prod version via Anastasiy's EM on her computer were back in the game !

It seems that transfer of preference files are somewhat random…

Has anyone got a clue of how is all of this working ?
I'm open for any coding suggestion that i wouldn't have think of, too. Maybe my extensions aren't robust enough.

There's no way we're getting sick and anguished everytime we have to update an Adobe Software...

Thanks !