Sailfish OS 4.4 removed most of the Lipstick notification categories (see /usr/share/lipstick/notificationcategories). As a consequence, sounds in chat notifications no longer worked for Fernschreiber (see https://github.com/Wunderfitz/harbour-fernschreiber/issues/486). With an older device I could guess that the option “x-nemo-feedback” was set to “chat_exists” for the previously existing category “x-nemo.messaging.im”. Setting that option explicitly brought back the sound on my device, but as you can see in the GitHub issue, it still doesn’t seem to do the job completely.
Therefore to sailors or others who know the details: Is there any complete documentation about the notification configuration options (especially the special x-nemo- ones) including the possible values? Neither Nemo QML Plugins Notifications - Sailfish OS nor https://github.com/sailfishos/lipstick/blob/master/doc/src/notifications.dox come close to actually providing the needed information…