Please provide all the information that can be useful to dig into this. Xorg version, desktop environment version, graphics card model, GPU driver and specific version.
BTW, did you try updating to the latest version of Xorg?
It seems we need a paid subscription to send data to NoMachine tech support so we haven’t followed up.
That’s obviously the norm. Except in the case data can be useful to solve a bug of general interest, like in this case.