I ended up getting read-only filesystem alerts for the USB drive, which was causing all these issues above. Not sure how I missed these errors the first time around. Now it makes sense why I couldn't adjust share configurations.
I do wish a descriptive error message appeared from the UI, like "Couldn't write updated configuration" rather than nothing.
IMHO It is annoying that Unraid is suspectable to a single point of failure with a USB even if recovery is always possible. Guessing there are opinionated topics around that design.
I'm also unsure how this occurred in the first place as I'm using a somewhat decent flash drive for my setup.