Just installed the updates and that did fix the issue. Thank you!
Great, at least we've got that.
The new architecture still is a bit weird in that it deletes all RandR modes but the one that was detected on the remote (i.e., client-side) screens, so changing the resolution within the session itself won't be possible.
This shouldn't be a huge problem in general since resizing is still possible in windowed mode and irrelevant in whole display or fullscreen modes.
Other than that, be aware that the new version still has other unresolved bugs, which include a huge memory footprint within nxproxy (server/client mode), slowdowns for no apparent reason (though only one user so far has reproduced this), random application crashes for software that uses a lot of X resources (e.g., Firefox/Pale Moon, Audacity, KDE Plasma, fvwm2, ...) and sudden connection drops (which may be related to the previous slowdowns and have so far only been experienced by one user).
Mihai