Dashboard gadgets fail to render after upgrading from 5.2.5 to 6.2 (m03)

Dashboard gadgets, in both the system dashboard and within individualized dashboards, fail to render properly after upgrading to EAP version 6.2 (m03). The following error is present where the gadget should be:

Error loading gadget from rest/gadgets/1.0/g/com.atlassian.jira.gadgets/gadgets/login.xml: org.apache.shindig.gadgets.GadgetException: Unable to retrieve gadget xml. HTTP error 404

I researched this issue, and explored the 4 options presented here (none of which could resolve the issue): https://confluence.atlassian.com/pages/viewpage.action?pageId=222200924

Is this a known issue with EAP releases?