Looking at a freeze frame from my helmet cam from the same time as the log, looks like you’re fully right, I was mistaken.
(the glass shattered recent-ish when someone else was riding the board (not sure how it happened) but i’ve been having the problem of weird logs for much longer then that)
Entirely possible the GPS module was/is damaged from my crash with @RedBeardTorgo earlier this year. It took a direct hit with the ground… 
Taking it apart, there’s definitely some scraps on the antenna.
Probably enough to reduce its effectiveness, and would explain the lack of GPS. Looks like I gotta replace it. Seems like they’re available on Amazon
Separately, also makes me wonder if the damaged GPS module was/is somehow causing the file corruption that I experienced.
Thanks for the help @janpom !