One of our customer have the same problem on 2 Red one camera
Two times, on 2 different cameras with 2 different Red drives, it was impossible to stop record!
The status was fixed on "post" and impossible to do anything.
They must unplungged the power to stop
But nothing on the media the clip was lost .....
They used the build 20.1.6 to correct the Sata Fault so any issue