Thanks for following up…
I got this figured out, the problem was compound and partially self-inflicted 
The first problem was that I had recently transitioned to a subdirectory deployment and had not remapped all the necessary paths.
I had also rewritten uploaded_avatar_id to nil for each user in hope that would cause discourse to re-download the profile images. Obviously I was mistaken about that and ended up restoring the field from a backup 
The other problem was that avatars were not displayed to the left of topics in mobile view, this turned out to be a bug in the events plugin.