I modded an S&W factory K-frame holster to allow a 2.5" 686+ to fit.
The last pair of digits on the holster are 32, where 3 means K-frame, and 2 means 2" barrel.
It's long enough for a 3" K-frame to fit without the muzzle poking out.
At first the L-frame would not fit, and it looked like the culprit was 1" long portion of the welt in the trigger guard side of the holster. The leather would hit the frame (below the address) in front of the trigger guard. I took a sharp 1/4" wood chisel and trimmed the welt using a push cut motion. The 686+ fit fine after that.
I doubt if that's a universal fix since holsters are different, but maybe you can look at yours and see if the welt is what's blocking your 686 from going into the holster.
There are two pics of the holster in post #19 of this thread:
https://thefiringline.com/forums/showthread.php?t=609522&highlight=woods