RegEx find and replace what am i doing wrong?

I think this is trying to lookahead ?

I am trying to change only the test without a space…

Test()
Test ()

This works in Notepad++
(?<=\S)[(][)] then replace with
()

This does not work in ATOM 1.44.0 ia32 ?
It finds it but does not replace anything.
I am totally new to RegEx so I may be doing something totally wrong ?

Thanks