One of the things I don’t see talked about in regards to picking technique is touch - the way you hold the pick, and the way it should feel when you pick interacts with the strings. Occasionally, I find it a lot harder to break through the strings, despite me seemingly doing the same motions as usual with the wrist and arm. One time, it was because I wasn’t letting the pick “flop” through the strings, or playing with enough “give”. One way I think about it is letting the fingers gripping the pick go past the strings a split second before the pick.
Yesterday I had this problem at the end of a jam - something in my brain changed, and even though I was apparently gripping the pick correctly, playing just with the tip and letting the pick flop as it went through, I suddenly had a lot of difficulty playing. When I got home, I realised that if I follow through/concentrate my grip with the bottom edge of my thumb closest to the strings(something which was unconscious) the resistance disappeared. It could be something else, but that was my perception.
ANYWAY the point I’m trying to get to is, what’s the leading cause, in your cases, of feeling resistance from the strings, or your pick feeling “stuck”?