[Users] claws-mail does not remember password even though the "Remember with password manager" option is checked

[lmfrm]

I had been using Linux Mint 18 Mate 64-bit and upgraded to Linux Mint
20.3 XFCE 64-bit recently.

After this upgrade, I installs claws-mail from the repository
and transferred all claws-mail settings from the old OS to the new.

It no longer remembers the password despite checking the "Remember
with password manager" checkbox. (I don't know what 'password manager'
it's referring to.)

I'm using pgp e-mail but it doesn't tell me if it's asking for the
account password or the gpg password--in any case, mine happen to be
one and the same.

~/.claws-mail/passwordrc appears to store the password there. Actually
a send AND receive, and for each and every account; I only have one
account with multiple aliases all using the same password (for both
send and receive). I notice the encrypted blob for the send and receive
pass are different, and they are also different for every account entry.

Gnome-keyring did not appear to furnish claws-mail with the password,
and because it was causing all sorts of trouble on my system I removed
it. It was importing sensitive private keys from my gpg keyring and
sharing them with other applications without my knowledge or consent.
Removing it made no difference to claws-mail that I can tell. I don't
think gnome-keyring stored my password unless claws-mail put it there.

My private keys are stored in my gpg keyring but of course, the
password is not because pgp keys are just encrypted blobs and don't
include passwords. However, I configured ~/.gnupg/gpg-agent.conf as
follows just in case it had anything to do with claws checking
passwords:
default-cache-ttl 999999
max-cache-ttl 999999
but it did nothing.

I checked ~/.claws-mail/accountrc and ~/.claws-mail/clawsrc but could
find no settings to change that might make a difference.

I just wish to not have to type my account/gpg password incessantly;
this is impractical.

Where might I be going wrong? Or is it a bug?

Thank you.