Stuck in 5th Gear and no 6th Gear.

Since October my 370z has had no 6th gear at all and once i go into 5th gear it gets stuck in 5th gear even after i put the shifter back into neutral. I can get it back actually into neutral by pushing the clutch in and out or just waiting for it to come out. When it’s running and stuck in 5th I cannot put the shifter into any other gear besides 5th and neutral (and 6th as it acts the exact same as neutral). When it’s stuck in 5th and the car is off i can put the shifter wherever but once i start the car it’s usually stuck in 5th regardless of shifter position until i stall it a few times. Even in reverse it moves toward a tiny bit and stalls.

Here’s what the shop has replaced: - throw out bearing - clutch slave cylinder - clutch, flywheel, pressure plate - realigned the shifter retaining plate - 5th and 6th gear synchronizers (still has common 5th gear grind so maybe they didn’t do it right?) - 5th/6th gear shift fork

Any ideas on what could be causing this? Considering just buying a new cd009 at this point.