What type of ESC you use? can you see some in-flight data? or reason for quit?

The Ice 50 has datalogging.  Turn on datalogging and record.  Look at the amperage and voltage at the time of the SQ8.  The SQ8 has a high draw and could low volt cutoff on a weak battery.  Have all of the episodes been on different or same batteries?  I think what Igor was suggesting above.

Hopefully, Ice datalogging was turned on already and the record will be there awaiting download.  Otherwise another flight to see what was going on.

Jeti Spin and Spin Pro have the error codes in the "measure" area for reading on the Jeti box, to expand on how that is available.

Whats your low voltage cut off set for? What ESC and timer? If a castle, I set them for a soft cut off and a low voltage of 3v per cell. Yes I know its too low, But as I've written before better to ruin a battery than crash the plane. Are you batteries fully charged and are you positive they are fully charged? Maybe you charged them to storage level by accident? Again I'm just speculating like everyone else here.

Never used this software, but looks to me like there were some early short test flights and two full flights on 6S, but the last 5 were on 5S packs?

Agree about the flights showing short tests, 2 flights with 6s and the  5s flights.  I haven't used the Castle for a few years so not as fluent as I was.  You can record one flight at a time using a setting with much more definition and actually easily follow the maneuvers.  When you are plugged into the dongle, go about the end of settings and set for high resolution.  You can then run a flight, down load it, and have the next flight erase and overwrite.  It is a little painful or tedious, but I took a laptop to the field and would fly, then look at the data, then fly again.  Also, turn voltage, amps, temperature and other settings that might help you.

You can look at some old tracings here on reply 26
https://stunthanger.com/smf/gettin-all-amp'ed-up!/old-dog-new-trics-old-plane-new-rogerio-fiorotti-timer/

and another here with voltage and good separation of maneuvers reply 7, and one by John Tate in reply 18  and another with some other data reply 25
https://stunthanger.com/smf/gettin-all-amp'ed-up!/another-dog-another-'tric-fiorotti-v4-4-timer-with-accelerometer/

I was able to follow maneuvers in sequence by looking at a finer tracing. You can see throttle, amp draw, voltage drop, and temperature rise with each maneuver.  Then you can see the OH8.  You can record all of the values and then only display what you wish on the graph so that it is not too jumbled.

If you don't want to use a laptop at the field, then record your last flight of the day and look at it at home.

I can probably refresh my memory on the recording settings if needed.  I haven't been using the Castle for a couple of years.