After updating to Supernova, I can only open a new message (Cmd-N) IF the main Thunderbird window is present. If it is hidden, a new message doesn't open up.
Thunderbird for Mac 115.3.0
Macbook Pro 14-in. 2021 M1 16GB
Hi @Tim_S, I have the same problem.Did you find a solution? Otherwise I would suggest to file an issue in Bugzilla.