Thank you for the response. I might have found a workaround that has been successful for the last 48 hours:
1. Create a new ad zone and set the wildcards for the height and width -- "*".
2. Create a new Google Adsense banner and set its height and width to something arbitrary. I chose 800x133, because that seemed close to the proportions of their full-sized Native ad format.
3. Assign the new Adsense Native banner to the new ad zone that has the wildcards for its height and width.
The Native ad format seems to be getting displayed and tracked properly on some test pages I created.
Just a workaround. Maybe in a future release, Revive might have an even greater solution. :)