I got the file back of the guy from YACF and it imported normally but it's lost most of the speed, power, cadence, etc data after about the 1.5hr mark. :(
I can have a look at it (at the byte level) if you want, alex @ username . org , may take a while though and can't do it during work time obvs. Promise to keep your puny power figures secret too.
Hmm. Manufacturer 256 doesn't appear in the example fit source files (although I doubt I've got the latest version). Could be reserved since it's 2^8.