As I said: it takes the last pair of opening an closing brackets - and having said that, it implies that there is a "first" pair of them.
Due to the greadiness of the * repeater, an expression like `((.*)) would include everything in brackets, with source
Cold (ft Future) (R3hab & Khrebto, KSHMR Remix)
the result would be
(ft Future) (R3hab & Khrebto, KSHMR Remix)
To be honest: use my suggestion on the files that have a closing and an opening bracket close to each other : ) (
that should work.
For all the other files that have only a single pair of brackets, use
Format string: $regexp(%title%,'.* \((.*)\)',$1)
and then replace every word that you don't want with nothing using a simple replace action (i.e. delete it).
Why is all this so tricky?
The data in the field TITLE is not only the title but also contains a featured artist and a version description.
Unfortunately, the ID3 standard does not offer dedicated fields to structure this data.
The brackets are no proper field separators as one cannot tell from the brackets what kind of data they separate from the rest.
I, personally, use <> to enclose the featured artist and [ ]to enclose the version.
This leaves the round brackets for the title data.
And with these separating, dedicated markers, it is much easier to get the required piece of data from the title string.
So coming back to the thread in
it might have been better to use other brackets than the round ones to add the featured artist.