The NoMachine server logs from Windows would be useful.
Please follow the instructions here:
https://www.nomachine.com/AR07K00677
Send them to issues[at]nomachine[dot]com
It seems to be the same issue already reported in this TR: https://www.nomachine.com/TR10L04643.
You can sign up to receive notification of the patch when it is released (most likely in the next update).