Moodle 1.9.17+
I have a dialogue on the front page for users to contact admin. It has been working fine the whole previous semester. Yesterday, I got 2 new dialog conversations started by students. Today, I see 2640 conversations open and waiting my answer, each from a different person,. When I view them, they are all the same, one of the two from yesterday (which I nota bene didn't answer). It seems that the dialog conversation was duplicated for many users.
Any known reasons for that? How could that happen? Database shows indeed a record for each conversation.
Mystery solved. It appears that a dialog on the start page does not recognize administrators as possible instructors, so a dialog for instructor-student communication has only an option "send to all users". However, when I open that dialog as admin, I do see all started dialogs, although technically I should see only one destined for me. So something does not work right. Anyway, instead of fighting this, I am replacing this dialog instance with the HelpDesk block.