We are now getting the following error when running one of our AppExchange apps on the Summer '17 sandbox preview.  All we've done is create a Visualforce page that references a component in our managed package app but none of the resources are loading.  Even adding a CORS entry does not resolve the problem.  All critical updates have been activated for the org and nothing has changed in our code.  Reverting to API version 39 for the VFpage does not resolve the issue, either.  Is there a bug with the Summer '17 release?

ERROR: Access to Font at 'https://rmhdsm--dev2.cs41.my.salesforce.com/visualforce/{snip}journal.ttf' from origin 'null' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.

We are now getting the following error when running one of our AppExchange apps on the Summer '17 sandbox preview.  All we've done is create a Visualforce page that references a component in our managed package app but none of the resources are loading.  Even adding a CORS entry does not resolve the problem.  All critical updates have been activated for the org and nothing has changed in our code.  Reverting to API version 39 for the VFpage does not resolve the issue, either.  Is there a bug with the Summer '17 release?

ERROR: Access to Font at 'https://rmhdsm--dev2.cs41.my.salesforce.com/visualforce/{snip}journal.ttf' from origin 'null' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.