I have been in contact with @dane22 on Github. First, we thought it was limited to a plug-in issue (and @dane22 received a "similar problem for his plug-in) but quickly, after being in contact with the plex team, it was understood as a more general issue.
@dane22 asked me to "move" the issue here so here I am.
This comment contains the log files the Plex team asked me to create.
I really need assistance to find the reason of this problem as my setup is essentially dead ;(
thank you.