I remember checking my clearances during that step of installation and everything was fine. But somehow I have a feeling that may be the problem.
On the P-11, the trigger needs to contact the aluminum frame
completely in the reset position without touching the plastic grip AT ALL. You should also check side-to-side clearance to make sure its not rubbing somewhere.
With the frame out of the grip, check that there are no worn out parts in your gun that could be causing a problem.
Make sure that the fit between your trigger and trigger axis is fairly tight without any slop or "wiggle room".
Check that the trigger axis contacts the back of the "pocket" at the reset position, as shown at the bottom of Page 23.
The bottom of the trigger should have about 1/8" of pre-travel at the reset position before the trigger bar starts cocking the hammer. If there is only minimal pre-travel, you may need to round off the front edges of the trigger very slightly as shown on Page 23 of the P-11 Trigger Guide. This step is not normally needed as there is usually sufficient pre-travel with the newer triggers, but sometimes it needs trimming. (Hint: Push the trigger into the reset position to "mark" the spots on the front edges that need trimming. Then round the edges slightly at these points.)
Even with your gun having a "new trigger" to get used to, and the long P-11 pull, it should still always reset easily once you release the trigger fully.
Did you hear back from your gunsmith yet?
Pops