Hello @selina,
Do you have any px4 logs from the original flight(s) which exhibited the flipping behavior? The logs contain the commanded and actual RPM (as well as many other things) and we can check what happened.
If you don't have any sensitive information (gps location that you dont want to share, etc), you could upload the log to https://review.px4.io/ and that will give you some information and we will be able to grab that log and further analyze it to parse the custom ESC messages that standard px4 flight review does not support.
Alex