Well it happened to me. You ride, then something goes wrong. It could be your connection, it could be a maintenance window. It could be something else entirely. But nevertheless you lost your workout. The ridden distance, the tough work up those hills, just got lost towards your account. Luckily the .fit files are recorded, so everything is not lost, just your zwift progress and this is what triggers me, into writing this feature request. I’m sure there’s a reason, they don’t want you to upload .fit files, but losing progress towards your account because of something you might not be in control of, is not ok.
So dev team. Please work towards a fix in this direction. It could be as simple as an encrypted secondary output file that you can use to “repair” your broken ride.