gencfsm has suddenly stopped being able to lookup up password for one stash in keyring

This is a weird one, running 1.8.18~ubuntu16.04.1 on Xenial. I have three stashes, two set to automount with the passwords stored in gnome keyring.

As of this morning, gencfsm has suddenly started prompting for the password for one stash. I actually copied it out of Seahorse into the appropriate dialog and it worked! But quitting and restarting and it is still reprompting, despite "Save password in keyring" still being set.

Any clues or suggests on "where to dig"?