How to prevent auto-pausing processes in an inactive user session?
Solution 1:
I run into this problem too because I switch between console and graphical virtual terminals on a regular basis. Xorg by design suspends its clients during VT switches, which is why its clients seem to "freeze" when Xorg's VT is no longer active. Wayland does not, so if the programs you need to stay running in a background VT support the new display protocol, use a Wayland compositor instead of Xorg.
One way to work around this problem is to run graphical programs on a local VNC server so that they never get suspended. This is the workaround that I use the most frequently.