BaseElements reports a field as unreferenced, but it can't be deleted because it's in use

There is one situation in BaseElements where you can have a field that is being reported as "Unreferenced", but when you try to delete it you get a message like the following :

In this case, the field isn't in use, but FileMaker is remembering an old calculation. For example in the screenshot below :

If you change the Access for "View", "Create" or "Delete" to Limited, you can enter a calculation. If you later change the setting to Yes or No, then FileMaker retains the calculation, and any references to fields, but not to Custom Functions used.

When you try and delete the fields used you will get this alert, even if the Access is now set to Yes or No.

Solutions

There are two workarounds :

Change the Access level to "Limited" and delete the calculation, then ok the dialog with an empty calculation. This will alter the option to "No" and remove any references. You can then set it back to it's original setting and close the dialogs. But you will need to do this for every option for every Table that used the calculation.

Alternatively you can go back to the main "Edit Privilege Set" dialog and change the Record Access level to something other than "Custom". When you Ok the dialog, FileMaker will forget every calculation used for every Table. But be aware that you'll also lose every custom option for the tables, so if you wanted to retain the View, Create or Delete options you will also need to reset all of these. This may be faster than editing all of the calculations though.