I read your post and what I see in the screen shot from teendoi is clearly split screen on his nüvi® 2797LMT so that should not cause a problem.
Yes if he tried the full screen JCV then there would be a problem. But that is not the case in his screen shot.

I think the file is corrupted and re-download files again should fix the problem via Garmin Express.

Then has this just happen or does this problem happen each time the nüvi® 2797LMT is updated.