Issue Detail Panel does not open if attachment is missing from issue, shows blobstore error

If an instance has been imported without attachments JIRA Agile will not open the issue detail panel in Plan and Work mode.

If the user clicks on an issue card the following error is shown instead:

Remote blobstore couldn't find an entry for attachment xxxxxx

The Issue Detail sidebar will remain blank/empty.

Workaround
Delete the Attachment reference from the offending issue.
or
Open the Issue in the normal JIRA view instead.