(must add as a reply to myself, as I can't edit my original post)
Update: inspecting the problem better, it seems it's related to local client only (and even not all local clients too).
By opening my EG project using the web interface, via Citrix dashboard, and using the Project Management to modify the application server in all the tasks at the same time, this problem don't arise.
The same: a colleague who is supporting me in the migration, reported me that, even using his locally installed client, opening my project and using Project Management, didn't incur in that bug. He have not been able, tho, to tell me which configuration setting to look at (and, possibly, to change) in my local client, to avoid having such problem.
To avoid spreading unuseful alarm, I tested such behavior on my migrating project (one project only, for the moment) multiple times.
I hope this update at least help who fell in my same pit.
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