UPDATE: As we checked together the "Token expired" trouble can't be reproduced and some discussion topics really haven't the text. So for now, UNA works there correctly. Why some records are empty is checked now.
Thanks to LeonidS for checking several backups/databases for the missing content. As it turned out, they could not be found.
I will have to live without them.
I would advise anyone in the same predicament, in fact anyone running a site which has valuable content, to be sure to backup the entire site with the database before any update or any other change done on the admin end.
Sometimes a backup done wirelessly may be flawed due to skips in data transmission for one reason or the other. If possible, backup from the router using an ethernet cable. It is faster and is more reliable.
Updates may rewrite files or cause them to simply disappear. Hence laziness where one feels that one can take a chance and not do a backup, could result in a man crying like a baby.