I'm not following or having any difficulty with connects. I'm on ST8 now but don't recall issues with ST7. You can only pick one face though. The other component has to be a keypoint, an edge, or axis.
Maybe a screenshot would help understand what's happening for you.
All of our hydraulic adaptors have the mates saved so when placed the connect is from the taper face on the adaptor and we used to be able to (in ST6) select the taper on the part to be mated to. Now we are presented with every option accept the tapered face.