There seems to be some change in Thunderbird when I used it this morning. The tab for "Address Book" has disappeared and it is now also impossible to right-click an e-address and EDIT it after adding it. This seems to be a glitch in your upgrade.

I have the same problem with losing my address book What's the solution? Lou Filo

I have the same issue. I use running Linux Mint as operating system, without change. Tried changing the default address book to 'All address Books' or Personal Address Book: no change. Uploaded all the addresses again: no change, except now I have duplicate of all the entries in the address book.

I use Linux Mint as operating system. Yestreday I installed Thunderbird (flatpack), which added a second Thunderbird app to my computer. This version DOES autopopulate the 'TO:' field as we'd like. But this is a new installation, so all my past messages and folders and other data are not linked to it. For now I use the original Thunderbird to receive and read incoming messages; 'replying' to a received message is easy. But if I want to write a new message, I switch to the flatpack installation. This isn't an acceptable long term solution, but it's made my life a little easier.