The above example does not include "Add some text here". The created page is blank. I've tried this with $wgCreatePageUseVisualEditor set to true and false; Maybe it is an issue with 1.27alpha, I don't have a 1.26 or below to test it with. The rest of the extension works fine.
Mediawiki: 1.27alpha (43e4b9e)
Create Page: 0.4..0 (4009737)