optics module and camera platform nut slot too shallow?
The nut slot for mounting optics modules and camera platforms often seems to print with some obstruction at the bottom of the nut hole. This makes the nut sit too high up, and not aligned with the horizontal hole for the screw.

This is enough to make it very difficult to get the screw to start.
The nut slot could be 0.5mm deeper to allow some wiggle room for this. The final vertical position of the optics module would still be correctly defined by the location of the horizontal hole for the screw.