Two of my slide controllers are affixed to the roof of the bays (I have to lay on your back to find them) but the bedroom controller is affixed to the back of the rearmost bay just fwd of the bedroom. Here's a pix of mine. Yours likely looks different.
Another place it may be hiding is under the bed, which is also where the bedroom slide motor is. That would s*ck, but if you can't find it elsewhere that would be the next logical place. Wherever it is, 100% guarantee it'll be in the last place you look!
I would try Newmar again. Answers you get sometimes depend on the person you're speaking with.
Good luck