@welshdemon did you ever figure this out, I am pretty much doing – stuck exactly where you are. I am going for older bbpress to newer bbpress that is part of a full site update and just want to bring everything in cleanly. It does bring in my replies, and they seem to be connected properly in the backend, but frontend, they do not show.
If i edit a reply, and just hit the update button, it will then show. I want to avoid doing that 1000 times.
Even if I export the topics from the new site, that show properly after I did the update trick mentioned above, then bring it back in (wordpress import) to test if it will import properly, it does not, has same symptoms a you mentioned.
