I purchased an EZVIZ DB1 a few weeks ago when Amazon had them for $80 and installed it with the power kit on my 24 year old NuTone LA-140 mechanical chime with 16 volt transformer. Everything, including the chime, works as expected, even after updating to the latest EZVIZ firmware. It came with build 191211, and was recently upgraded to build 200904 using the EZVIZ iOS app. Maybe I’m one of the lucky ones, or maybe I just haven’t experienced these issues yet, but (IMHO, at least) it’s not just the recent firmware upgrade causing these chime issues. I really wish they would document their firmware changes with release notes showing what’s new and what bugs have been fixed, like most other hardware/software vendors do.