Example 1: Created blog by selecting this page as the Blog Page from the Theme settings - more tag is activated and sidebar looks ok
Example 2: Created a custom template with a blog element, assigned the page to this template. More <!--more--> tags do not work correctly, they are converting in <span> rather than . Also notice the sidebar has tags throughout that mess with the formatting.
Discovered this when attempting to set up two pages (using custom templates) to pull from different categories.