I know that BfA screwed up some addons and this one is one of them. This gives you a list of your current Battle Pets and is supposed to allow you to pick which ones you want as "favorites" to show up in your LDB. In the config there are various check boxes (have no problems checking and unchecking these boxes) and buttons to control things. One of the buttons is supposed to toggle all the pets either on or off. Clicking it does nothing, all the pets checkboxes stay checked.You can try to "manually" unchecking the boxes but they STAY checked. I have made sure that I am using the latest ACE3 libraries.
There are other problems with this addon pertaining to maps (BfA REALLY messed with these) but I have these parts disabled for now so I can get the main functionality of it working.
I have uploaded the addon to drop.me so that it can be downloaded and viewed in entirety (not going to be one of "those guys" who give barely enough to look at to try to solve the problem).