Haven’t seen this issue discussed before. The inside door handles of both my 2015 328i and previously on my 2013 X3 have developed a stickiness where you grab to close the doors. No, it’s not because I eat sticky candy while driving. It seems to be either deterioration of the black underside of the handle or some seepage where the black back of the handle meets the wood grain front. I’ve tried to clean with a Goof-off product but the stickiness remains. On the X3 it seemed to be deterioration of the rubber inside the handle, which I ended up covering with black electrical tape. Not a perfect solution. Anybody else have this issue? Any success getting rid of it? Not a major performance issue,  it certainly irritating. Thanks for anybody’s thoughts. 

Morning David

Welcome to the Forum

Not heard this before, but now you have started me thinking my E53 the leather steering wheel and the door pull did start to get dull and sticky. After talking to a car detailer I changed to Chemical Guys leather cleaners and treatment. It took 2 or 3 cleans to rejuvenate the steering wheel the feel was totally different door handle easier

I don't know if your problem is the same but worth looking at what cleaners have been used

Dave

@dwcarp I've read something similar in another forum, you might want to take a look here https://x3.xbimmers.com/forums/showthread.php?t=1707064&highlight=door+pull