Are ;you shifting at the right time?
I had much the same trouble until listening to a conversation at the LBS about shifting and force on the cranks.
The advice was to spin up to where there was very little pressure on the pedals a bit while shifting up. Or, if you were almost there, letting up on the force on the pedals for the shift to the bigger ring.
I tried it on my way home and had no problems with shifting afterward. If I try to shift while mashing...it's back to the original problem.