Imported workout has wrong name

I’m uploading structured workouts from Final Surge and copying them into the Workout file for Zwift, where I then expect to see them under Custom Workouts.
I’ve only been at this for a few weeks and without exception I’ve not be able to find the workout. What has been there has been a workout from the past (which wasn’t there when I tried to do it on the day).
Today I tried an experiment - I deleted all the structured sessions from the Workout file - then copied in my session for tomorrow, labeled “Wed Oct 28” and went to swift to see what would be there. There was a single session listed under custom - “Mon Oct 26” - which was not there when I tried to ride yesterday.
So I’m stumped. Then I opened the file to find that it’s actually tomorrow’s session, just with the incorrect name.
Any ideas?