On some of my imports, the category tag on the listing block will either not appear at all, or it will take several hours to appear after the import. Sometimes they appear immediately, though.
I am not sure about the time delay because I start messing with things trying to get it to work, get frustrated and walk away, and then when I come back sometimes they will appear. So, not sure if it is purely time based or if it is a setting I just happen to click on or off? Could it be related to transient caching by any chance? One time I deleted all the transients and I noticed the categories appeared. Maybe a coincidence? I am using it on my site located at prgrants.info