I gather it functioned fine before the trigger swap?
Sig uses a proprietary BCG, hell about everything on it is proprietary except the stock and grip! My 716 made three trips in for work till it functioned....so far. I have not swapped the horrid factory trigger yet due to this, don't want to have to swap it back if it has to go in again. Troubleshooting online is hard because Sig keeps changing up parts from time to time, like the dual extractor set-up. I follow the rifle section on SigTalk, many there have changed to Geissele triggers without issue but I do not recall seeing anything on Elftman triggers yet.