Other than mentioning you are using the "Mercury style" I have no idea which version of Bandlab (or possibly Sonar) you are using. This is important because there was a problem back in Sonar days with hidden tracks but it wasn't pinned down and fixed until Bandlab by Cakewalk was released.
If this IS still happening in Bandlab by Cakewalk my suggestion is to create a brand new template in Bandlab and not use any older templates you created in Sonar.
Do a small test by opening a brand new project and creating a new folder with several tracks.
Try hiding a few tracks in that folder, then close/reopen the project and check for re-appearing tracks.