Hutch
When mine was at the dealers, it did something similar but in this case did not ratchet, sort of stalled. The dealer was showing me how the slide worked and he hit the button and the bottom started moving out and the top did not.
I mean a significant amount. Like 3 to 4 inches.

Well he did stop thank goodness and he retracted it and then tried again time pushing the top out by hand at the same time. Heard a big, crack, the seal let go and out she went.
Part of the deal on this camper was I did not need a big 1hr long sales explanation on how to use it but I wanted 10 minutes of there top tech that works on slides point and talk to me, so we did from under the camper.
He said the biggest issue they have is the seals. Things get stuck in them and then torn needing replacing. The one point I left with is to use 303 protectant on them often to keep then flexible and pliable. He said you can buy the spray on foam slide lube they sell, but the 303 is better and you spend less. So I have done the treatment about 2 to 3 times a year and never had the problem of the slide sticking in since.
However our slide does not stay in as long as you said yours was. Since we camp all year round the longest it has ever gone is 6 weeks maybe 2 months with out ever being extended. So I agree with Mike, most likely the seal stuck.
If this happens again, try rocking the top of the slide by hand if it will at least move some to break it free. If it never budged, well the hand crack you did is probably the best way to put some pressure on it then try and push to knock if free. After seeing the dealer do the bottom out and no top moving trick…

. I would not crank a lot of inches before you tried and pushed. If the bottom is moving, the top has too soon or elese.
Which reminds me, I need to go put some 303 on the seals now. Have not yet done this year. Thanks for the reminder.
John