Can scripting be used in 'Action-Replace with regular exp'

I have been using regular expressions and scripting recently, and discovering the power of MP3TAG, but have a problem. A script (or set of scripting functions) which works as intended in the action 'Format Value' to extract some text to another field, does not work when used unchanged in 'Replace with Regular Expression' to delete the text from the original field. The documentation for Scripting Functions says that they can be used in both these Actions, is that true? When I use the Script in 'Replace with RegExp', nothing happens, and although I get a message saying that 1 tag has been updated, it has not.

Can anyone confirm that Scripting can be used in both of these Actions (Format Value and Replace with RegExp)?

I can't because it cannot.
And if you look closely, you will find the input fields
Field
Regular expression and
Replace with
in the action of the type "Replace with regular expression"

and the input fields
Field and
Format String
in the action of the type "Format value".
So these are completely different approaches.