Dual Y-Axis TMC wont move at the same time

Basic Information:

Printer Model: Self-Built
MCU / Printerboard: BTT Manta M8P
Host / SBC: BTT CB1
klippy.log
klippy.log.zip (491.8 KB)

Describe your issue:

Greetings, we have a custom-built cartesian-style printer that has a dual-motor Y-axis (pls don’t ask). We’re in the progress of setting up klipper on a Manta M8P, featuring TMC2209 drivers.
The following problem arises:
When stepper_y and stepper_y1 are “on” at the same time, stepper_y throws an error. This happens for example when homing. Using FORCE_MOVE the steppers can be moved without a problem, but when using it on stepper_y and then stepper_y1 (or vice versa) the same exact exception is thrown. If M84 is executed before moving the second motor, no exception occurs.
So far we have checked all the connections for continuity, the steppers are fine and so are the drivers themselves, we have tried different drivers and different slots on the MCU board, thus we are slowly running out of ideas.

Thanks to anyone who has an idea.

Cheers