I'm currently having a very similar problem. I have a compact crank - FSA Gossamer with a Shimano Tiagra FD. For a number of months, I always rode in the big chain ring. Lately I have started using the small ring on some steeper hills. It shifts perfectly going from the large ring down to the small one but when I try going back up, I have to stop pedaling, hold the shift lever in and start pedaling again slowly. and sometime the chain will go on up to the large ring. It is frustrating.
I have had the bike in the shop several times for them to adjust things to no avail.
Today I was in the shop and they told me to bring it back in. They want to change out the chain ring. They suspect the ramps on the ring are not right for some reason.
I don't know if that is the same problem you are having but it could be.