sudo rejects password that is correct

sudo (Which I have configured to ask for a password) is rejecting my password (as if I mis-typed it) I am absolutely not typing it incorrectly. I have changed the password temporarily to alphabetic characters only, and it looks fine in plaintext, in the same terminal. I have my username configured thus:

myusername ALL=(ALL) ALL

I am using my password, NOT the root password, which are distinct. Just to be sure, I've tried both (even though I know the root password is not what I should use) - neither work.

I have added myself to the group 'wheel' additionally, and included the following line:

%wheel ALL=(ALL) ALL

I'm kind of at the end of my rope here. I don't know what would cause it to act as though it was accepting my password, but then reject it. I have no trouble logging in with the same password, either at terminal shells, or through the X11 login manager.

Another possible cause is that systemd-homed is not running. Check it's status with

systemctl status systemd-homed

If it says something other than active, use

systemctl start systemd-homed

to start it again. Note that you need superuser privileges in order to run that command. As sudo is not working, you might try logging as root using

su root

and the correct password for root (usually not your regular user).

Oh what the heck, here was the issue, I guess?

https://bbs.archlinux.org/viewtopic.php?id=142720

pacman -S pambase

fixes it.