Microdata are a strange set of attributes which are ONLY defined in markup, and have no relationship to the underlying Document Object Model node. As such programmatically defining an element and setting a property on it with a given Microdata attribute will not work:
https://codepen.io/iambrosius/full/jOvXBBG
One can read more about microdata here: https://developer.mozilla.org/en-US/docs/Web/HTML/Microdata
The fix is to remove itemscope being a boolean attribute, because that opts into a transformation as a DOM property, which is wrong.
Filip Ambrosius