Referral Exclusion filter not working in Google Analytics

Question

I noticed a spike in referrer spam from the domain "rhympasgnuiz.top" for one of our sites. I have been following guides on how to exclude this traffic from GA but so far nothing I've tried has worked.

I've tried the guide here: https://www.megalytic.com/blog/how-to-filter-out-fake-referrals-and-other-google-analytics-spam

It's possible to "verify" the regex and I always get the message:

This filter would not have changed your data. Either the filter configuration is incorrect, or the set of sampled data is too small.

If I enter a catch-all regex (.*), I get a list of all Referrer domains but the domain in question is NOT present.

I've also added this domain to the "referral exclusion list" with no effect.

My settings for the filter are below. Thank you for any help!

Answer 1

I just had quite a long exchange via Google Live Chat and I was told categorically that it's NOT possible to exclude traffic that has already occurred... "You can fill the complaint form. This is how it is".

I don't get why it's like this, perhaps I've misunderstood how GA is meant to work. Anyway, I suppose I have answered my own question. 🙃