VTOL Skywalker 1900 stuck in hover when switched to FBWA, eventually motors stopped - fell out of the sky! OSD included

Hi, got some strange behaviour I was hoping someone could help with.

Was flying my VTOL and had decided to test RTL mode. This is where the video below starts. The plane climbs to 100m (which it was supposed to but at the time I didn’t realise it was set to climb to this altitude so I kept switching out of this mode as I thought it was flying away. I was flying line of site so wasn’t looking at the OSD.
At 01:33 you will see that the plane drops out of the sky and loses 20m altitude in about a second. At this point it was in QRTL (in the OSD top left this looks like “M_21”), then I switch it to QSTB, and then finally to FBWA. It continues to hover as demonstrated by the low forward speed on the right hand side and the high current drawn (~65A) (bottom left). Without warning the motors all stop and the plane drops nose first to the ground but fortunately the motors spin back up and I was able to land QSTB as normal.
Still no idea what happened and I’m not very good with the DF log to figure out what happened. I’ve uploaded the log if anyone has any opinions on what happened?
I’ve flown today and it seemed a bit hard to keep in the air in FBWA but that was probably because it was too windy.

Thanks

Mike