As accurate, nice -and for the most part well thought of- the xTool frame is, the cable routing definitely needs additional attention.
The way the cables are routed with zip-ties makes it very likely that at some point one -or several- of them will restrict the axis movement in some way.
Sounds like that’s the case with Your machine.
Could also be some other mechanical issue, but that’s the one I’d check first.
I’m in the process of installing “robotic-/energy chains” found on better machines to house and route the cables on mine, but the weather has been way too nice to be tinkering inside .
The original cables are obviously too short to be routed in that fashion, so that approach requires new cables as well.