Regarding your first two points, this is a long shot but maybe it will help: I had a very similar problem with LastPass where password fields in the LastPass UI kept being pre-filled with my master password, even in places where there seemingly should never be pre-filled. It turned out that I had accidentally enabled my web browser's autofill/password manager functionality, and every time I visited the LastPass extension's internal URL, my browser was autofilling every password field with the password that my browser saved.

Once I turned off the password manager feature of my browser (I didn't need it anyway since I was using LastPass) it solved the problem.