No attachments shown in paper clip column of classic view

Using "classic view" in the mail app makes it easier to handle huge amounts of emails.

Unfortunately after installing Sierra the paper clip notifying that the respective email has an object attached is not shown in the "paper clip column" anymore. And the number of objects attached is missing, too.

This concerns to every email downloaded via POP after the upgrade from El Capitan to Sierra while all the old emails still have the paper clip and number of attached objects visible in the column.

However all attachments are shown in the respective email. But if one needs to check several emails if there are objects attached or not it's much easier to have the "paper clip column" in the overview.

Does anybody have an idea how to fix this?