As for the missing items in your database you could try deleting the database that v18 built and the next time you open Kodi it will rebuild from your v17 info again. It is possible that there were errors during the initial conversion.
As for the missing items in your database you could try deleting the database that v18 built and the next time you open Kodi it will rebuild from your v17 info again. It is possible that there were errors during the initial conversion.