Regular Taxonomy support in CustomPress suddenly no longer working

I have a custom post type that supports regular taxonomies. I've been categorizing these "posts" successfully for a while now, but all of the sudden the category meta box in the Quick Edit space in admin, as well as the full edit page, no longer shows up. I've tried unchecking "support regular taxonomies" in CustomPress settings then checking it off again (which felt very silly, but hey why not try), and I don't have any caching or anything. I also didn't make any changes to my site since last time I visited. On the front-end of my site, the posts I've already categorized still show up as part of those categories, so that's good. But I can't categorize any new posts in this custom post type.