No idea why it’s marked as resolved.
This will be improved early on in the 1.1.x series which is coming soon. See my site https://cartpauj.com/forum/ for the new beta.
For those needing help now, make sure you have at least 20-30 posts in your forum before you try a search. The search doesn’t work well, if at all, when there are only a handful of posts.
For those who are more technically inclined, or for those who want to pester their hosting company for a quick helping hand, you’ll need to make sure that the wp_forum_posts table is running on the MyISAM engine, NOT InnoDB. If it’s InnoDB the search will not work period. Also, after switching engines, you may need to set a FULLTEXT index on the text column in this table.