LED light bulbs not working when installed in slideout

My suggestion would be to find the 12V feed to the light circuit going into the slide and just reverse the - and + and that should solve the issue. On one rig we had, I had to do that because it was reversed in polarity in the slideout and the item I was installing would not function as wired.
On my present coach, some of the bedroom ceiling lights are of incorrect polarity and some LEDs will not work correctly.
Hope this may help. Happy trails bert