I'm about to do the rear brakes on my 2016 328ix LCI single piston and found this post that confirms the details above with a screen shot in English from TIS
https://f30.bimmerpost.com/forums/sh....php?t=1354470
Seems like you are not supposed to turn an extra 90 degrees if you reuse the M12x1.5 bolt, but as bthomas518 mentioned the repair guide says they should be replaced.