Sorry about HB not working after the update. Likely, you are going from 1.x to 2.0.0, right? The way that addons store data has changed significantly since the legacy version, and as such upgrading does cause the blacklist to get forgotten. It CAN be recovered if you follow the instructions from https://github.com/kainsavage/HistoryBlock/tree/v2.1.0#migrating-legacy-blacklist

Please let me know if I am misunderstanding and file a bug report with as much detail as possible on Github.

Thanks!