Similarly to comment #15: updating libpam-kwallet-common, libpam-kwallet4 and libpam-kwallet5 to version 4:5.12.7-0ubuntu0.1 from proposed repository and rebooting didn't change anything for me.
Only the workaround on comment #5 is currently useful, but I don't know which other problems it may cause...
As an additional test, I uncommented again the 2 "pam_kwallet" lines in /etc/pam.d/lightdm, rebooted, and the problems reappeared.
Similarly to comment #15: updating libpam- kwallet- common, libpam-kwallet4 and libpam-kwallet5 to version 4:5.12.7-0ubuntu0.1 from proposed repository and rebooting didn't change anything for me.
Only the workaround on comment #5 is currently useful, but I don't know which other problems it may cause...
As an additional test, I uncommented again the 2 "pam_kwallet" lines in /etc/pam.d/lightdm, rebooted, and the problems reappeared.