In order to display a topic using the new parser you need to ensure that flexwiki.config does _NOT_ have

<DisableNewParser>true</DisableNewParser>

which causes all access to the new parser to be shut off.

Then in the topic you have to add a property DisplayUsingNewParser with a value of 'true' as in this topic. You can verify that the new parser is being used as the division between sections of the borders is now a visible rule rather than just empty space when using the original parser