Imported Blog Posts Not Showing Publicly

So I used the import tool to bring in some Wordpress posts into the Perch blog. They imported fine and are showing up in the Perch admin, and they are set as "Published", but they don't show up using perch_blog_custom until I edit the post and click the "Save" button. Why is this happening, and is there any way to automate this?

More Info: In the Perch Admin, when I list posts "By Category", none of the imported posts show up, so it looks like they're not categorized. How does the categorization mechanism work for posts in MySQL? I went poking through the perch3_blog_posts table, and it seems the category is set in the postDynamicFields column, by setting possibly categories: [], or blog_cat: [], so I wrote a script to do that. It seems to have populated the categories multi-select on the post edit form, but the actual posts still aren't being categorized properly until I physically click the "Save" button for each post. There must be an easier way than going through 100s of imported posts and "Saving" each one...