Empty prefs with default profile / feeds don't update (having problems with mariadb? come here)

I’ve had this issue too for a while, but after I did a bit of cleanup on my feeds, removing or marking as “do not update” those that are dead, it went away so I didn’t consider it relevant to report and didn’t link it to the upgrade from 10.3 to 10.4

ok, some new finding.

according to https://jira.mariadb.org/browse/MDEV-19820

when I prepend

set session optimizer_switch=‘rowid_filter=off’;

to the reference query that @fox gave, the result is correct, without needing to change the = to LIKE.

Moved all my databases to 10.3 and ttrss seems work fine now.

Posting just for making known that with the release of MariaDB 10.4.7 the issue related to empty prefs is gone.
It might also benefit the other issues referred in this thread.