Do the racks behave this way when added to a new song and then down the road they lose the gain sliders? Just want to be sure whether it’s related to a corrupted song save or a corrupted rack save. Also, are the racks always the same ones or is it random?
Do they work in older songs? Did they ever work right and for how long? It sounds like you should send the bad racks to @brad for evaluation. Could help all of us to know what happened!
If you go into the Rack and then File -> Rack Options, do you have the option “Let parent song control this racks gain and state” turned off.
When this option was originally introduced it removed the gain and state settings from the parent song display - to enforce the idea that it’s not controllable by the song.