This is the same problem I'm having, the thing is, I replaced the master and slave cylinder and i ended up getting a stainless steel clutch line aswell. When i started to bleed the system, I would build pressure but the slave cylinder was not engaging all the way how its usually supposed to. I had someone press the clutch in all the way and I went under the car to check it out and the slave cylinder was barely pushing the fork. I am honestly lost because there is no leaks anywhere. Would you by any chance know what might be the problem or have some suggestions on what to try.
I would suggest doing what ended up solving my issue. From what I understood from the research I did was that once I removed the fluid line from the slave cylinder I introduced air not only to the slave cylinder but also the master cylinder. So no matter how many times I pump the clutch pedal the master cylinder was not building up pressure and therefore neither was the slave cylinder. In my situation the fork was not moving at all so it could be that I had more air in my clutch system then you. Both me and my father followed the service manual which said to only pump the pedal 5 times then open the bleeder valve. When that didn’t work I pump the pedal until I got tired which was well over 100 times and never got any pressure (the pedal kept sticking to the floor). That’s when I came along a RU-vid video regarding bench bleeding the master cylinder. At this point I had only changed the slave cylinder so I decided to bite the bullet and replace the master cylinder but before installing the new one I made sure to bleed the master cylinder outside the car hence the term bench bleeding. I’m not sure if you want to do this since you already installed the master cylinder and would have to remove again but let me tell you I was completely lost as well. I also did not have any leaks and was starting to think I had a plug somewhere in the lines. Here is a link to the video that helped me out regarding how to do the bench bleeding if you want to try it out. m.ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JlllJPUH9pQ.html