Installed BC.
Entered email as username and password
Set it to encrypt some files. They had green ticks but never seemed encrypted.
Each time I exited BC they were still normal.
In settings, I selected to use password when opening BC. Assuming the password would be the same one as no new one for opening the application was asked for.
Reopened BC - it wouldn't accept the password that went with the email when I set it up (copied from KeePass).
Thankfully all my files are still available as BC never actually encrypted a thing.
I've now reset the password associated with that email using an online form - so I can no longer assume Zero Knowledge if there ever was ZK.
A bit at a loss.