(Not at the studio to verify same) is there volume automation on those tracks or are you dealing with automation, while the Region automation takes priority over track automation project’s setting might be at stake?
I didn’t try it but I wonder if a possible workaround would be to import the project into a fresh new one but without selecting the ScoreSets among the data to be imported…
Try the folIowing :
after one of the note is selected : using the arrow keys
set the cycle (locators) around it : (default US KC= ⌘U)
then issue the Select All Inside Locators command (default US KC=⇧L)
I wonder if rebuilding (at least partially) the project by importing data into a fresh new project (not using an existing template) could alleviate your issue?