10spd or 11spd?
Would always look at chain and cassette wear first (and double check too), check that the gears are indexed correctly too. Have you left the chain a link or two too long per chance? Take the chain off, and check the jockey wheels are spinning fine too (just cos they “look” ok doesn’t mean they necessarily are).
If it’s 10spd the mechs didn’t have as much tension in them as the 11spd mechs do, you can’t officially increase the tension, but it’s worth checking that you’ve got the B tension screw wound out enough (not too close that the jockey wheel hits the largest cog, but as close as you can get away with).