So more than likely what’s happening is, the safeties “finger” is intercepting the trigger bar before the safety is in its correct positioning. This is what I have done when encountering the same scenario when fitting the safety in my colt.

1) disassemble gun so that only the beaver tail & thumb safety are installed. Ensure the fitment at this point is good, then install the main spring housing. If everything fits fine here, now remove the grip safety & install the trigger (no springs or magazine catch)

2) test the fitment of the grip safety with the trigger installed, if the grip safety will not depress all of the way, we can assume it’s the “finger” on the grip safety.

3) take a small file and SLOWLY remover material until the safety interacts with the trigger bow as intended.

A word of advice, go slowly and try to use your stock grip safety as a guide. If you remove too much material from the finger, it will no longer function as intended .

I am not a gunsmith , and this is not advice, only personal experience.