Problem: I could not get my responsive Adsense unit (from Google) to show up in the "banner" position module while using the Joomla Protostar template. When I put the same code in a different module position, it showed up immediately after refreshing the page.

Possible Solution: After wrapping the Adsense code in a paragraph tag that was explicitly 100% width and height of the container, then the ads started to show up. This could be one big coincidence, but the ads started to work immediately after I did this, so it seems to be related.

<p style="height:100%; width:100%;"> [Adsense Code Here] </p>

Ref: Joomla version 3.6.5. Hope this helps.