Regular Expression includes first word of the tag when formatting a value

[accidental-fart]

I'm trying to move the featured artist into the artist tag using Format Value and $regexp.
My current action looks like this:

Field:
ARTIST

Format string:
%artist%\\$regexp(%TITLE%, (.*)\(feat\. (.*)\), $2)

but for example on the track "What This Means (feat. Ouse)" by Powfu, it formats the ARTIST tag to Powfu\\What Ouse

Any help would be appreciated, thank you so much!

[ohrenkino]

You have a space character in the regular expression behind the first comma.
$regexp(%TITLE%, (.*)\(feat\. (.*)\), $2)
->
$regexp(%TITLE%,(.*)\(feat\. (.*)\), $2)

[accidental-fart]

Oh thank you so much.
Now I have a new problem, whenever I'm tagging stuff in bulk, the titles without featuring artists just copy over into the artist tag, do you know of any way I could fix that or should I make another post for that?
Thank you once again.

[ohrenkino]

I would never apply an action "blindly".
In this case I would filter for the files with "feat." in the title:
%title% HAS feat.
and then apply the action.