Does the hammer cock manually?
It sounds like the slide is not working the disconnector correctly. If the hole for the disconnector (in the frame) is not according to specs, the slide or sear spring may not position the disconnector the way it should.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)