Gunsmithing Help - AP5 Failure To Go Into Battery After First Round

Put a new brace (SBT5) on my AP5 Core today and am having issues. After firing the first shot, bolt no longer catches spring and I am unable to put the AP5 back into battery without removing the brace, realigning the recoil spring, and putting the brace back on.

My assumption it’s an issue with the brace but I’m not sure what that issue could be.

Please help, still only have less than 100 rounds so fair chance I’m just unfamiliar with the platform.