It appears at first glance that this issue wasn't addressed for the 1.98 Old Man update. Overview data still isn't being read from pbo in Mission folder.

KK, let us know if it would be helpful for us to make a new ticket splitting this issue into two, namely:

The Steam-related issue discussed here appears to be related to the process of publishing a mission to Steam Workshop from Eden editor. In that dialog, a mission description and image can be uploaded along with mission (after agreeing to Steam Workshop legal BS). IMO, the data entered in that dialog should NEVER replace data already included in mission (e.g. overviewText, overviewPicture, data in Eden Attributes, etc.) UNLESS the user clicks a switch/toggle to that effect. Such a toggle doesn't exist AFAIK.

Could it be true that BI delegated all overview data to the Steam system and removed the ability to make pbos with all overview data self-contained? Seems unlikely to me......

Great! I am so glad that it's a bug! The system is still reading data from the Steam workshop page, and at least some of that must be intentional.... Perhaps the system is meant to read data from Steam if no overview data is available in mission, and the bug is preventing the reading of mission data, thus resulting in data being read from Steam?

I tend to think that the decision to kill user-entered overviewText and overviewImage in description.ext/Eden Attributes and replace them with Steam data was a corporate one, and no further thinking went into it. If so, this is a real shame. The most obvious reason why it is a bad idea is that a mission's description on Steam workshop is meant for "marketing" and information purposes, to provide potential players with data like gameplay elements, links to forum threads, other web sites, etc., whereas overview data typically entered by mission makers are designed to get players psyched to play by putting them in the mood/headspace of the mission. I find it hard to believe that BI would stealthily do this without informing the community, even in the biki. Perhaps I missed it, though.