[Klipper] Enabling Bed Mesh Levelling Squishes Dense Parts

Problem: Parts that are dense or have a lot of moves in one layer seem to get compressed vertically when using ABL. When the part is done it looks squished, and the toolhead is a lot lower than the software thinks it is. For the cubes shown, it's about 4 mm lower than the firmware thinks it is. Turning off bed mesh levelling makes the issue go away completely, but I unfortunately need this for large parts. To confirm, usually I get flawless prints but this issue has arisen on models which linger on a single layer for a long time. Large plates or small dense objects seem to be affected. Things I've tried: checking extrusion factor - single-walled cube is spot on different parts of bed - same issue on larger parts tramming bed tramming x gantry - it does this at the start of each print creating a new bed mesh - it does this at the start of each print after heating the bed reassembling the z axis updating klipper turning off perimeter overlap - at 0% for all tests below adjusting start and end fade in Klipper Config Hardware: this is on an ender 3 pro V2 with bl touch, microswiss DD, rpi 3 with BTT SKR Pico, and dual z axis motors. The bushings are free in x/y but very little slack in z. I've also tried tightening them Test prints (see number of dots on images): 1. PASS no bed mesh, perimeter only 2. PASS Bed mesh, start 1 end 0 perimeter only 3. PASS Bed mesh, start 1 end 10 perimeter only 4. FAIL Bed mesh, start 1 end 0 80% infill no overlap 5. PASS No bed mesh, 80% infill no overlap 6. FAIL Bed mesh, start 1 end 10 80% infill no overlap (cancelled at about 57%) 7. FAIL Bed mesh, start 1 end 100 80% infill no overlap (cancelled at about 15%) 8. FAIL Bed mesh, start 100 end 200 80% infill no overlap (cancelled at about 58%) 9. FAIL Same as 8 but with bushings tightened. Cancelled at about 50% Additional comments and files below 🙂