For the above, I’d also used FG drupal to wordpress plugin, maybe mixed up a bit; couple of other plugins too, inc for categories.
I figured might be an issue in this.
Went to bbpress; and chose option to clear the forum.
Then, re-imported.
I got loop on item 16; found others had experienced this with import. So, stopped it; looked at forum.
Initially, forum showing 0 posts, topics; even though posts and topics actually present.
I ran the tool for repairs; seemed the same.
But, went away, returned to site and the forums page has the numbers of topics and replies.