I was using the V29 whistle model as a 3D printer test piece on my MPCNC, and with 3 attempts to print it, it had a large shift in layer at one Z level only, @ about 16mm. I was printing at 30mm/s but had my travel speed (non print speed) set to be a lot faster @ 160mm/s. Slowing that down fixed it, I think I used 120mm/s. Took me ages to work it out (well 3 attempts over as many days) because I thought it was thermal overload in the drivers being just one shift… Except when it always happened in the same spot I realised that was quite unlikely. Strange it only happened on exactly 1 layer each complete print though, goes to show the limits of the machine may be affected by a previous move. I am using 4 TMC2100 drivers for the X & Y though (enjoying the silence!) so my machine’s specs. are a fair bit off what’s standard.