Hi aarond,

I can see you are having problems with the destination Url of your backup image. Great question, this is a bug and we apologize for this, this has been already reported and escalated to the team in charge. This issue is only in the Studio, you can double-check your destination Url is working fine on a test page after trafficking the creative.

The backup image will always have the default exit.

I hope this information will be useful for you.

Thank you for your question
Regards