ELB rule looks to be ignored

Hello,

As a first ELB/Listerner rule in front of our web servers, I set up the following:

IF: Http header name user-agent is *Ahrefs*
THEN: Return fixed response 403

For whatever reason, the rule is simply ignored and our servers continue being loaded by unwanted Ahrefs bots. Is it because there are 2 wildcards in the value match or do I miss something?

I however found an example if AWS documentation where ir looks to be authorized: https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-listeners.html.

Many thanks in advance for any help.