What dictates / determines an Available-Hidden column is locked in an application?

I am unable to toggle certain fields in Columns in the Cash Receipts Applied Detail application. The toggle says Locked when I try making the column visible.

Please can you confirm what determines Available-Hidden fields are Locked and will not toggle to being visible (if hidden) when a user attempts to make the field visible in the UI?

Thank you.

Previously discussed here: Available-Hidden columns are locked

When something like an app setting or logic Hides an Available-hidden (or Shows an Available-visible) field, it will end up being locked despite seeming as if it should be toggleable. I will link this thread to the backlog idea that exists requesting an improvement to the UX in this situation.

Ah, ok, thanks @ian.p