Welcome to the forum Newfoundland......does the slide actually seal at the top or bottom, in the middle of the slide, or is it not sealing in both places? I would hope a 2019 would have seals that were still in good condition but you never know. I would also inspect the roof of the slide to make sure no tree branch or other debris was pulled up against the outside wall of the coach and is jamming the middle area from coming in fully. Less likely is that you can also have small items roll under slides on the interior that may result in a jam, but I would expect the next time the slide goes out any floor damage from that kind of jam, might become apparent. If the seals are in good condition and in place, you could try measuring the distance from coach wall to extended slide outer wall at both ends and the middle; top and bottom, to see if all are the same distance. This would confirm the slide itself is not warped or damaged somehow and the slide mechanism is aligned at the ends at least.
PS: it must cost a few bucks to get your coach to/from the mainland I assume?