All of my filters using the parent field (which were working last week) are now returning errors that Field 'parent' does not exist or you do not have permission to view it.

When I begin to type "parent" in the query, it no longer suggests/populates parent as an option.

The parent field does show up in other filter results, but you cannot sort by it.

I am a site admin and have access to all projects/features/products, etc.. I have also checked with other admins and they return the same error.
I've been checking other fields and, thus far, I have not found similar issues.