Version 2021.03.06.0114 lost M3U channels

After update, cannot reload M3U for Pluto or STIRR so getting zero channels.
Worked on this for over an hour with no success so I turned off firestick and ran errands for 3 hours. When I returned and powered up TV and Firestick, the M3U channels are back and the DVR has somehow repaired itself!
The M3U refresh was apparently just delayed after updating to latest beta version.