Quote Originally Posted by Andy340 View Post
Had a similar issue with chain snagging on shifting down to small ring (usually when under load) - I tried a lot of adjusting which didn’t work and finally resorted to checking every tooth on big ring for imperfection. Found a tooth that was gouged (by feel as not obvious to my eyes) and had burrs that must have been catching chain ( not sure if this was original issue or a result of first bad shift which caused damage)

Replaced the chain ring and issue went away.

May not be cause if your issue but worth a look if not already ruled out
That's a really good candidate, definitely worth checking - thanks for the idea.