one thought..... have you tried cycling power. I have found that often this helps with these weird issues.
I suggest pulling a battery cable to completely kill all power to the coach for a minute or so, then reconnect and try.
Oh, another thought.... the slides have an interlock with the chassis.... so they will not work if the chassis engine running. I think some might also have an interlock with the parking brake. You weren't by chance starting the chassis engine while cranking in that slide, were you?
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