When I battery the bolt to the "open locked" position, I normally hold my thumb on the bolt catch/release, Duh, but it gets stuck at the begining of the battery?

I have to battery the bolt to the open position before engaging the bolt catch/ release.

Is this a problem with a new weapon, or bolt release?  Or??

The weapon is new with 400-500 rounds through it, on occasion it malfuntions at the beginning of the cycle, and it's stuck as if -  read 1st sentence-!

Is their a certain shape to the engaging part of the catch/release that must be obtained for proper functioning?

Is it a non-shrouded DPMS carrier? I had a DPMS carrier that did the same thing. From what my feeble mind could determine, during manufacturing the carrier was deburred excessively. It only takes .005-010 of material removal on the rear of the "fins" of what used to be the shroud, to let the bolt catch drop in to the "groove" in the carrier. This causes the condition you describe.  I wish I had pics and better terminology, but that is probably what is happening.