Hi everyone:
The export to STEP has a small bug. Nothing of another world and think that can be easy fix it.
In all dialogs, i are asked to use Relative path. In other words use: Out/generated_file instead /home/me/…Out/generated_file
The STEP export has not this, but even after cut manually to let only relative, now i see the absolute again (and wrong absolute path)
The screenshot looks like from KiCad version 8.0 (now unsupported).
Try it on 9.0, click Export in the dialog, save the PCB, and report to GitLab if the bug still appears.