It depends, I would think, on whether you saved the file after you muted it or not.

If not, I could see why the files are opening unmuted. My DAW does that. I can close it after saving and upon reopening that same file, everything is exactly as I left it..... time line in the same place, record active on a track, etc....

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.