Creating a task doesn't set the value to the default in a custom field. When anything in the task is changed the default value is set as normal. This results in history looking like this:
User created this task.
User added a subscriber: User.
and after some time
User edited the task description. (Show Details)
User set Custom Field to Default.
This might be the reason behind Phabricator should only notify changes to the "Security" field if it is indeed changed in Wikimedia Phabricator.
Ah, now I see that @jdloft here and Negative24 in Wikimedia might be the same user. :)
I don't think the "without a description" part is correct. I think just creating a normal task with a normal description is enough to seed the problem. The custom field value is not set at creation, but only when someone edits the task (even without touching the custom field at all).
That is correct (reproduced with https://phab-02.wmflabs.org/T17). Updating the task...
This new bug sounds like a different manifestation of the same problem: https://phabricator.wikimedia.org/T94155
I'm experiencing something a little different using a custom select field.
If I create a task, via UI or conduit, without explicitly setting the custom field, it appears to be set to NULL instead of the default value. This is based on the fact that the custom field is not displayed in the web UI for the task.
Later if I edit the task, the custom field's dropdown box is populated with the first option, instead of the default (which is actually the last item specified in the custom field definition).