I'm on 3.1.9 (1186) right now, and I just noticed that previews of Scrivener projects no longer render. Instead, I get a preview for 'recents.txt' that contains one or more GUIDs:

I've trid it with several Scrivener projects that rendered previously.
I haven't had as much time or work that required Marked in the past few weeks, so I'm not sure if this might have start before 3.1.9 or not.
This isn't an urgent fix for me, as it will be a week or two at the earliest before I work with Scrivener again because of other things at work.