Thank you for your review. The latest version of ESR is 60 now, meaning Mozilla is no longer supporting Firefox 52 ESR. I've tested on ESR 60 and 1.1.12 seems to be working fine. I do not have plans to provide continued backward compatibility for versions that Mozilla is no longer supporting, since that can become an open-ended endeavor.

EDIT: I just tested ATH 1.1.12 on 52 ESR, on both Windows and Mac, and don't experience the problem you expressed. Perhaps there is a particular setting in ATH Options which triggers this issue, or maybe the profile you are using in 52 ESR is corrupted. (Note: you are not able to switch between 52 ESR and 60 ESR using the same profile without having data loss)