"@misses" block in overdue_notices.pl (lines 535 to 540 in http://git.koha-community.org/gitweb/?p=koha.git;a=blob;f=misc/cronjobs/overdue_notices.pl;h=e83bd39bd2d9d2976d046ad27b75bc736c982a7e;hb=HEAD version) is conflicting with HTML-formatted ODUE notices.
Can you add some more information? Does this still appear on current versions?
There was never an answer to the question asked - setting to INVALID.