I have long had difficulty with compliments myself. I started going to therapy about two years ago and early on noticed that I had a hard time when my therapist complimented me. One thing that I noticed was that I always ran the compliment through my own filters to evaluate it. And similar to what you said, if it was something I already knew I did well it didn't really seem like a big deal to me, and if it was something that I didn't think I deserved a compliment for than I more or less just dismissed it as uninformed I guess.

After talking with a friend about it, I decided to work at trying to let the compliments in with out as much filtering, to just feel them I guess. I was doing a lot of work on other things in therapy at the same time which I imagine also were factors, but I did eventually get more comfortable with compliments to where now it is easier for me to just appreciate them and feel good without needing to analyze them so much.