Extreme Horizontal MP4 Content Tagging as Rec.601

This may not be bug specific (or really even a bug) to the Beta as I've been able to replicate the result in AME 20 as well.

When outputting mp4 content through AME that is of an extreme horizontal nature (4224w X 72t), the content gets tagged Rec.601.  Settings in AME are: Profile - High, Level - Unrestricted. High10 will render the same Rec.601 result. When outputting more traditional aspect ratios such as 1920x1080 with the same AME settings the content gets tagged Rec.709.

Is there an mp4 setting I'm just missing that will get a 709 result with extreme horizontal content?

I've attached a screenshot of settings as well as Media Info color metadata.  Thanks in advance for any insight into this topic.