Bug tracker
conversion and search tables (fulltext_native) (fix completed in vcs)
however, the conversion never tells you to do this. ideally, at the end of the conversion you would be asked "search tables need to be built. would you like to do that now? (Y/N)", where "Y" takes you to the right place, and if the user answers "N", a reminder to do it later would be presented in a clear way.
moreover, when you search for something after the conversion, you are not told "search indices were not rebuilt", but rather "No suitable matches were found".
when you go to the ACP, it seems that the search indices exist, and there is no hint that they need to be rebuilt. you need to go through 2 steps: deleting them, and then building them.