We restored the site collection to a different web app, but no luck. Access denied! It seems to have something to do with unique permissions. but this is the only site collection that is doing this.
The access denied occurs when trying to access the site column gallery under site settings as well, but no other _layout item.
It is exclusive to subsite owners and site columns.
I only have Site Collection admin rights.
If anyone has any suggestions, they would be greatly appreciated.