After properly aligning my cam synchronizer and it lightly engages in the cam gear it will not drop all the way down onto the oil pump shaft and I do not know why

 

Welcome to the form

Assuming 4.0l 1995-2000 engine?

The oil pump drive has a hex shaped shaft that has to line up with Cam Synchronizers hex shaped base
So after synchro is in place manually turn the crank with socket wrench 90deg one way and then the other way and hex parts will line up and synchro will drop into place
Then turn crank back to your mark and recheck sensor alignment

repeat as needed until sensor is where you want it