Help! nDisplay multiuser : render clusters freeze when saving map

We have an issue with multiple render clusters (on two different computers, or on a single computer) in a multi-user session.
Everything works well until we save the current map (from a third computer which has the director role) : all render clusters freeze and then time out (closes).
The same action works well when using only one cluster. Anyone has a clue to what the source issue could be?

Also the issues is not happening on simple maps, only on medium/complex ones.

last few lines of the cluster log:

Hello. I have a similar problem, so I’m leaving a comment. Have you solved this problem?