Hi Roxana,
That is really weird, and I have no idea why, but for some reason, the UV Editor doesn’t seem to recognize when Melvin goes into Edit Mode. I tried earlier Blender Version (even before 2.90, when this was made), but the result is the same each time.
A work-around is: use the ‘melvin_unwrap_result.blend’ and immediately press CTRL+E > Clear Seams.
Then you can start fresh.
