Steps to reproduce
Setup a Backbone sync, configure one or more issue types -> save config
Create a new issue type, add it to the issue type screens of both projects
Clean Backbone cache in Backbone sync
Add new issue type to configuration
Backbone shows the issue type including its icon. Also, Backbone is synchronizing issues with this new issue type.
Backbone does not show the issue type icon and also can not synchronize issues with the issue type.
Disable / Enable Backbone and reopen the configuration. The issue type icon should be shown. Also, retry the related errors from the troubleshooting.
It works as expected if the project involved in the synchronization is associated with the new issue type in the Issue type schemes page.