Coupler is specified as PC4-M5 in the text of the BoM, has a 4.6mm hole in the CAD body (Filament motion sensor > Sensor body > Body2) but has a PC4-M6 connector in the CAD as well.
I'm guessing this is an issue only with the part inserted in the CAD, as both the holes and the BoM seem to indicate a PC4-M5. The walls would be a little thin with an M6 connector, possibly, though I've not printed it yet.
https://github.com/EiNSTeiN-/roadrunner-filament-sensor/tree/main/CAD
https://github.com/EiNSTeiN-/roadrunner-filament-sensor/blame/964c20d2c45e33bc7731ea71be599f5dc0b7bed2/manual/BOM.md#L47