Sometimes your top sidebar ad will be targeted to view in the first screenview or "Above the Fold".
We recommend that ads don't display until the second screenview (make sure you've enabled the Optimize Ads for Desktop Pagespeed options) and you will need to retarget where that first sidebar ad is displaying.
With Trellis, you can easily move where your top sidebar ad displays, by using the Mediavine Sidebar Ad Hint widget.
To add this widget, head to Wordpress > Appearance > Widgets and add the Mediavine Sidebar Ad Hint widget to the sidebar:
Be sure to drag the Mediavine Sidebar Ad Hint widget below the last widget that appears in the first screenview.
Once you've added the widget, you're all set! Just view your site in an incognito window to make sure your top sidebar ad is displaying.