Apologies for not updating this earlier. Two fixes, the second of which I suspect is the actual fix:
1. Upgraded to the newest version of Arthemia Free: https://colorlabsproject.com/themes/arthemia-free/
2. In looking at posts and code, I noticed that posts with a featured image set (in addition to the custom ‘Image’ field timthumb.php had required in the earlier Arthemia) were both showing the image and generating proper slashes, not 2D% (I think) in their place.
So, basically, go back and set featured images on your posts and see if that gets them generating properly. If not, maybe switch to the new theme.
