I wonder if your issues are similar to mine. I’m using a 5’x10’ utility trailer as my frame, I initially spaced my anchor points as far away as I could, then realized that made my usable area really “short” near the center. I adjusted my anchors, my “frame” is now roughly 1900mmx1420mm, which should give me a roughly 1000mmx600mm working area, so I set my calibration area to 800mmx400mm. I’ve run multiple calibrations that were seemingly successful, but if I try to jog around the work area after calibration, I end up with multiple slack belts. If I jog too far, I end up with tangled belts that require disassembly to respool.
Here’s my latest post on the issue: