Sounds like you're changing that option for two or more sources at once. They can be different. :-)
Also, "Monitor Off" continues to feed OBS's recording and stream, via the Tracks selection. If "Monitor Off" kills those, then you have a non-standard audio configuration. I've done that myself a few times, on purpose, for a specific reason each time, but you kinda do need a specific reason to do that. In art, you can break any rule you want, as long as you know what the rule is, why it's a rule, and why you're breaking it this time.
And if you need support for a non-standard config, you need to explain all of it in detail to prevent wrong assumptions. Screenshots and diagrams are much better than the wall of text that the explanation would have to be otherwise.
