Take out the extruder stepper and rotate the shaft by hand and feel if there is binding at any point. I think I mentioned I had this same issue on my direct drive printer in your previous post. It would work fine until it didn’t and randomly act like the nozzle was clogged. When printing, I think the load on the motor is going to be greater than feeding filament through into open air, which may exacerbate the problem.
You’ve xhecked the hotend a bunch of times so I would focus on other areas. Something else may have broken at the same time as your nozzle swap which may just be leading you on a wild goose chase.