[Defender Pro] Defender STILL over-active in blocking IPs

Hi there,
I’ve submitted two related tickets about this, and it seems this is coming up again. For the last couple of weeks, we’ve been getting intermittent reports from clients on different domains that either they, themselves, or a public reader/user (without a login) is getting the message:

The administrator has blocked your IP from accessing this website.

We’ve run through ideas that maybe it’s Hummingbird, but we’ve still never full been able to resolve this. I’m also not sure what makes Defender decide to block an IP, other than 404s and login attempts, but we’ve got 404 detection disabled to try and keep these IP lockouts down. Disabling Hummingbird does NOT fix the problem, but clearing the IP ban list sometimes does. Truly, the only thing that helps each time is deactivating and resetting Defender, which is not a permanent solution.

I’m really at a loss now. Some clients are getting angry that their readers are being blocked from viewing their sites, and other clients are angry that they can’t log in — if you guys have an idea, I really really could use some support. If not, I’m going to have to abandon Defender, because this issue has been ongoing for more than a year and we can’t deal with it anymore.

Support access for this site is enabled, but as I said, this is happening across our network now.