Motor stopped and I had to run Setup Motors FOC wizard to get it going again

Hi guys,

First post, been lurking while building a project dirt bike.
I have a Trampa VESC 100/250 with 84V LiFePo4 prismatic cells and a QS138 90h motor running through a 5 speed gearbox.

I ran Setup Motors FOC wizard originally with the 6.02 firmware the vesc came with and the bike ran OK. Without any field weakening it topped out at 70kph and the motor got hot enough for the VESC to limit current (it was a 35 degree celcius day too). 
Before making any further tuning I decided to update firmware to 6.06 and ran the Setup Motors FOC Wizard again. I noted the Hall sensor values came out slightly different this time. I bumped up the motor amps from the wizard setting of 202 up to 245 amps and the absolute max motor amps to 390 amps. I also gave it 120 amps of field weakening (via a couple of steps as it just went better with higher amps) starting from 65% duty cycle. My battery amps are set at 150 amps. 

I took the bike out for a ride this afternoon and the result was very pleasing with 110kph achieved with acceleration enough to put a smile on my face. I gave it a hard time here and there in short bursts checking that the motor was not getting hot from time to time. I was just about to head home and came to a stop to check the battery capacity in the Ant BMS app and the bike wouldn't respond to the throttle when I tried to ride off a minute later.
To cut a long story short, I managed to get the motor to kind of run by turning off the reverse rotation, and it would run slowly (still in the direction I needed...) and I could walk beside without having to push the rather heavy bike. 

20 minutes in to the walk I decided to run Setup Motors FOC wizard again just for the sake of it. The wizard completed successfully and after resetting up the throttle I was able to ride the bike home again (slowly because it was dark and also I just wanted to make it home without more problems...). 
Once home, I used my laptop to reload the saved motor configuration from just prior to going on the ride. The result was the motor refused to turn again. I ran detect Hall Sensors from the FOC Hall Sensors tab and it radically changed the Hall Sensor values but the motor spins up excitedly as it had before the drama began. 

Has anybody got any clues as to what may have happened?
Is there anything I should check to try and make sure it doesn't happen again??

Cheers,
Jason