I can confirm this bug also from my latest round of dashboard testing (25.-26.3.2024), tested on both Firefox and Chrome with different user permission levels.
In case a playlist contains exactly one entry of unknown duration: should we display the calculated duration instead of Unknown duration?
TLDR: Yes, the calculated duration should be displayed.
In such cases Tank currently has a feature to automatically expand the duration of the media source to the length of the timeslot. Since Tank Playlists are now moved to Steering, this feature should either stay available server-site in Steering or done by Dashboard. Please decide with @eigenwijsje what makes for sense to you.
@kmohrf I'm wondering how the new logic is working, since episodes media do not necessarily have a timeslot/broadcast date anymore. Is the length of expanded items still stored somewhere?
I thought otherwise we may need to re-introduce the logic, where Engine was calculating the length of expanded items during scheduling (cc @chrizz).