Do you have a service manual? There are actually two bleed valves for the hydraulic system pertaining to the clutch. Additionally air is bled from the actuator from the three bleed valve screws on the side of the Actuator closest to the gear box. If I understand correctly, you didn't break any of the hydraulic lines except at the quick disconnect, and when you took the bell housing off to replace the F1 sensor? What year is your car? Do you have to remove the thrust bearing in order to take your sensor out or can you access it without breaking any of those hydraulic lines? The early model cars like mine you had to disassemble it like I did in all the photos above. In the later cars they changed the design so you no longer had to.
Pertaining to the hydraulic lines going to the clutch, there is a bleed valve by the quick disconnect coupler, and again there is one that is mounted to the bell housing itself. They both look similar to bleed valves on the back of brake calipers only they are larger. They usually have a rubber grommet covering them to protect them from dirt. There cannot be any air in those lines or it will not engage the slave cylinder/thrust bearing assembly. It would be similar to air in brake lines where you push the brake pedal and it compresses the air in the brake line and your foot goes to the floor without engaging the calipers/drums. Same principal....
Additionally, there is a bleeding procedure in the Service Manual. It's done with a SD2/3, or Leo system so I'm not sure why someone told you that it self bleeds, that's incorrect. If that was correct they would not of added the bleed valves in the system. Again they are identical in operation as brake bleed valves. Basically what the SD2/3 or whatever interface they are using does is pulses the F1 pump to build the pressure (similar to pumping the brakes) once the pressure is built they slightly loosen the bleed valves to allow the air out. This is done until it bleeds straight hydraulic fluid and there is no longer air in the line.
I can tell you from experience that I have by accident left the quick disconnect coupler disconnected one time and no "CC" light was triggered and the Leo system didn't pick it up either. Of course there wasn't any clutch engagement and the car stayed in neutral. This being stated I re-read where you posted......
What prompted you to decide to change the F1 sensor? If there were no codes how did you come to the inclination your F1 sensor was faulty? Additionally, you must have a newer model car where you can access the sensor by not taking the thrust/slave cylinder out. If you can switch into R, 1st and 2nd that means you have pressure pushing that thrust bearing forward, which wouldn't be happening if you completely split the system apart to remove the sensor. So you must of only had to take it apart at the quick disconnect, and not in the bell housing to get to the F1 sensor.
So the car was originally doing this, R, 1st and 2nd, which prompted you to only change the F1 sensor? But now the car is still doing this? I'm a bit lost take me through how you diagnosed this problem as only being an F1 sensor problem, and not something else without having any diagnostic codes leading you this way.