I worked on an older car one day and had a similar problem. The clutch reservoir was empty, so we filled it up and got all of the air out of the lines. The car went into all gears fine when the car was off, but wouldn't when the car was running. After bleeding the lines tons of times just to be sure there was no air in the lines, we still had the problem. We ended up starting the car in first gear and when the vehicle was moving, the clutch started working. I believe it was the boot in the slave cylinder that kept getting hung up or something.
I don't know, but it fixed the problem for us. The method is not something I would really recommend, but we were working on an old car so it didn't really matter.
I don't know, but it fixed the problem for us. The method is not something I would really recommend, but we were working on an old car so it didn't really matter.