Dive activity recognition

Ok, I asked this in the Dive Android app forum, but will ask here too.

I've edited a Dive activity FIT file, but when I import the file to Connect Web, whilst everything looks fine on Connect Web, and Connect APP, the activity does not transfer to the Garmin Dive App. 

I've essentially replayed the FileId, FileCreator messages into the new file, and set the Sport and Subsport appropriately. What am I missing to get the Garmin Dive app to recognise my edited activity?