Using Typo3 8.7.0 I encountered the problem, that page.10.variables with styles.content.get resulted in an empty page as soon as there actually was any tt_content element. Turns out the problem is this:
<f:layout name="Default" />
Seems like the layout must not be named Default, because Typo3
has some conflicts with that. As soon as I renamed it to Main the problem was resolved.