Problem

In Jira Data Center, it is possible to set a Default Priority for Issues. It is possible to set 'None' as the default, but if this is selected, it is not respected. When an Issue is created, it is required to have a priority, so instead of none, the Issue will be created with a priority from the middle of the list. 

Environment

Jira Data Center

Steps to Reproduce

1. Edit a Priority Scheme to use 'none' as the default value for an Issue Type.
2. Create a new Issue.

Expected Results

No default value for priority will be selected.
The expected result if the field is hidden would be that the field would allow a 'none' priority, or would mention that it will be forced to choose a default.

Actual Results

Jira allows the admin to select None as a default, even though it is not treated as a default. It then selects a default from the middle of the list, with the higher priority breaking ties.

So in a list like:

1. Highest
2. Very High
3. High
4. Medium
5. Low
6. Lowest

Jira will default to High when None is selected, because it is the highest of the middle two.

Workaround

Explicitly set a default priority to control the behavior. A priority of None is not really possible because Priorities are required.