Lately I have been noticing a few issues with importing FIT files from a Garmin Descent Mk2i:
[*] The computer name sometimes is "Unknown Unknown"
[*] The serial number "randomly" changes
[*] Air integration is unreliable, I get at least two different gases on every dive. The first gas has no air consumption and some weird negative usage duration. The second gas has correct air consumption but either a negative or incredibly high duration.
This seems to have started after Garmin released firmware 16.00 for the Mk2i, back in November '22. Looking at my imported dives these issues never occurred before with firmware 14.10 or older.
The dives show correct data in Garmin Connect on the web and in Garmin Dive on mobile, letting me believe these are import/parsing issues in MacDive.
Let me know if you some FIT files from the newer firmware releases are required to debug.