Looks like I am having the same issue. I upgraded from v78.x to v80.0.10 last night and it just seems cPHulk is not working at all now. I have not touched any of my cPHulk settings. I also have all countries blacklisted except US.
Getting hundreds of login failure notifications and the cPHulk History for one day blocks looks like this.

Getting hundreds of login failure notifications and the cPHulk History for one day blocks looks like this.
