Symptoms

When creating a new Issue, custom Issue Type Avatars are missing (shows a blank/white box image) in the dropdown however throughout the environment (in the Issue Types Administration and Issue Details) the correct avatars are seen.

Diagnosis

If we run a Browser Inspector and look at the Console while viewing the Create Issue page, we see that the URL for the Avatar Images are not coming in correctly:

For some reason the URLs are being generated as: https://domain.atlassian.nethttp//path/to/the/image.png and obviously fail since they are invalid.

When we find the Avatar in the Issue Types Administration page, the URLs appear to be correct:

Workaround

A workaround was found by re-uploading the Custom Images for the Issue Type Avatars.  

1. Choose  > Issues. Select Issue Types
2. Edit the Issue Type that shows a missing Avatar when creating a new Issue 
3. Update the Issue Type Avatar by clicking on the select image link and upload the custom image
4. Click Close and Update to finalize the changes.

If you do not have a copy of the avatars on your workstation, you can save a copy by going to the Issue Types Administration Page (Choose  > Issues. Select Issue Types) and Right-Click and Save the needed avatar(s).