Got a little gunsmithing mystery and need some help diagnosing this. Have a Gen 1 Phantom with a holosun 507c riding the slide and some DIY upgrades: CZC comp hammer, 13# hammer spring, brand new OEM recoil spring, CGW floating trigger pin and reduced spring, and an action polishing. The upper has an extended firing pin and matching springs. All of this was done thousands of rounds ago. No major operating issues. The issue predates the 507c install.
Currently about 1:10 rnds will stop the gun like I’ve never experienced before. Gun will fire. Spent round will eject. New round will not fully chamber. Slide will be 1/4 inch out of battery. You can push it forward BUT the trigger is “dead” absolutely no action to it, the hammer is not cocked. Can’t second strike -dead trigger and it will not cock even manually recock. The hammer is not engaging the sear at all, just tension from the hammer spring. At this point I have to manually eject the round and rechamber a fresh round. This is not an ammo issue - I wish. Tried numerous brands and weights. If I rechamber the failed round it goes bang every time. Not the recoil spring (I think) the issue would pop up once in awhile but it has gotten worse. Installed a New OEM spring but that didn’t do a thing. It’s not a tight chamber. I’ve pluck tested the barrel. Tried many different mags but no help. I can’t replicate this, or any issue, while dry firing. Tried upside down, gangster style and it works like a champ.
I’ve got this apart on the bench and it looks great. At this point I’m thinking it might be a timing issue due to a worn over polished part like the trigger bar or sear or disconnect, but that’s a big guess. (and why wouldn’t it chamber???) could this even be a timing issue and what part should I replace? Would lowering or raising the recoil spring weight do anything? I’m not a gunsmith that understands how all the parts interact like some members. I’m more a clever monkey that can follow pictures and directions LOL. I have also been successful at find springs that fly off the bench and getting all the parts back into the gun.
So any thoughts on what to do next?

Summary: Just fired a round. Ejected case and almost loaded a new one. Trigger and hammer have not reset. Will not second strike, need to rechamber and reset the action.
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