Hi WesR,
I think you have one too many closing parens.
This works for me in v9.0.1:
site=.*?(?=\&)
This does not:
site=.*?(?=\&))
If you think the double close parens is correct, please post the text you are testing against.
As a note, v8.2 was not even an official release but it's very old.
You might check your upgrade eligibility.