I just allowed two additional users into my local test install. They changed a value in my panel setup, and it updated the text file appropriately, but no matter what I do I can’t see the change in-browser. I was not having this issue before they signed in.
Do you mean you can’t see the change in the Panel or you can’t see the changes they made on the frontend?
I figured out the problem. I had a field in my site.yml blueprint. I decided somewhere along the way to move it into a sub-page blueprint, but neglected to update my template, which was still referencing the original content file.
So just an FYI to noobs like myself: If you have a blueprint configured with a field, and save a value through that input, it does -not- get removed from the content .txt file if you remove the field. The only way I know of to remove it is to either save an empty value via that panel before you remove it, or just manually clean it up in the .txt file itself.
For your clean up day: https://getkirby.com/docs/cookbook/extensions/content-file-cleanup