This is a little weird, so I will try to describe as many details as I can.
I have a MacBook Pro with NoMachine 7.10.1 sharing my desktop. I can connect to the notebook over my network from my Windows desktop with NoMachine 7.10.2, everything works as expected. I use my notebook to virtualize various environments for retro-computing purposes, specifically I keep a Windows 98 VM (running in vmWare Fusion) and a Mac OS 9 VM (running in Qemu). If I launch either of the virtual machines and try to interact with them the mouse will only move downward and to the right in the VM (+1 to X and +1 to Y regardless of the movement of the actual mouse). This happens in both Fusion and Qemu but ONLY when I use NoMachine to connect to the MacBook host. If I interact with the VMs directly on the Notebook, the mouse tracks correctly. Even weirder, if I depress the left mouse button the mouse will begin to track correctly until I release the mouse.
To attempt to summarize:
Windows Desktop connected to MacBook Pro Notebook with NoMachine, then launching a VM on the MacBook Pro causes the mouse to be uncontrollable inside the VM.
I tried to capture the problem with a short video you can view here.
The first thing I went looking for were options in Fusion/Qemu and NoMachine that tinker with the mouse, but I haven’t been able to affect the problem in any way. I would love if someone more knowledgeable about tweaking NoMachine could give me some ideas to try.