Unchecking "Repair Disk" under certain circumstances (no idea which) causes the SYSTEM registry hive to not properly dismount. This isn't too troublesome, as repair disk isn't exactly needed with the System Recovery menu intact. Another possible bug is that the Windows Store seems to be crashing unexpectedly still, but I think this may be due to an instability after removing Xbox services along with various other built-in applications, not Winreducer, but again this is unclear.
Edit: Removed sections regarding OneDrive & Proximity
Edit: Removed sections regarding OneDrive & Proximity