Hmmm... Well the fix of specifying the specific version of the pyschlage library didn't work, obviously, but I was afraid that would be the case.
We may need some help from UD on determining why the plugin won't start, despite the PG3 log file saying it's starting fine. I think there is a file called "crash.log" that may contain the information we need, but there is no way to access it without SSH to your device. Even if we did know exactly why it wasn't starting, I don't know that we could fix it without also using complex commands via SSH.
Can you open a ticket with UD on this and maybe they can point us in the right direction?