Me too, or at least when it comes to grbl. Nothing in the configuration stands out other than $101 being exactly 8X $100. Different micro-stepping ? Could be x&y are mechanically very different ? In any case that's not the problem.I'm really new to this
I've had bad luck with UGS and had to move to bCNC. UGS would flake out in unpredictable ways but I suspect java in Linux could be the culprit.
If you have the Arduino IDE on your computer there's a quick test. Plug everything in and open the IDE's serial monitor (it's under the tools tab).
Set the baudrate to 115200, and the line type to "carriage return". Grbl should respond in the window but if it doesn't send it a "$$".
If that went okay send it a commands like "G01 Y-10 F500" or whatever is safe at the machines current position. If the machine moves properly using IDE you're probably having the same luck with UGS as I experienced. If it's not behaving in IDE hang in for some better quality of help to wander by.