my question is that is it a bug, a feature, how can i correct this, etc.
The display part is a feature. I guess the thinking is if a file was modified six months ago, you probably don’t care about the exact time. But if i was last week, you might be more interested in the exact time. So that’s why the displays are different.
As far as not showing up on playlists, that I don’t have an answer for. Can you see on the database what the timestamps are for date_added on those?