Users report erratic delivery of forum postings when they have selected digest deliveries rather than deliveries as single messages.

The most recent report of a problem noted: Yesterday, (18th) I received a Moodle digest with my posts of Jan 12th and then other's posts from Jan 16 and 17.

The only change we've noticed that seems, possibly, to immediately precede the appearance of the erratic delivery of digests was the installation of the recent security update to version 1.5.3+

This appears to be documented by others (see http://moodle.org/mod/forum/discuss.php?d=37027 )