I suggest that you remove the upholstered panels covering these wing walls on the inside for a look-see.... to see if it's just an edge condition or throughout
On mine the buttons are simple snaps with matching upholstery wrap, so they just snap off...pry off with a screwdriver...to reveal a screw zip out the few screws and it comes right off.
I had a leak from above..on the roof...that caused mine to do this. My whole wall wasn't gone but there was rather large rotted areas in it. Surprised me too because I never smelled any musty or damp odors at all...and i feel sure it was rotting since before I even bought the thing.
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