Column 'ItemChildCount' does not exist on an External List

A rather strange change has occurred within one tenancy in SharePoint Online. All external lists connected to an Azure SQL database are returning the same error message "Column 'ItemChildCount' does not exist. It may have been deleted by another user."

The same external content type is set up in another tenancy and is being consumed without any problems. I've tried recreating the content type and the list in both the current site and another site within the tenancy, but the problem reoccurs.

All of these lists where previously working and no changes have been made to either the content types, connection, secure store or underlying data structure within SQL.

Any ideas?