Connect to XML Forms Libraries with Site Content Types

I am trying to report on data from various XML Form Libraries on SharePoint Online. These libraries utilise a site content type. There are about 12 libraries in total.

In Power BI Desktop I'm attempting to create an OData connections to each library, however the columns that are available to me are very limited. I can choose columns that are native to the XML Forms Library, but I can't utilise any of the columns that come from the site content type utilised in this library.

For example the below feed works successfully with limited columns:

https://tenant.sharepoint.com/teams/site/subsite/_api/Web/lists/getbytitle('Current Applications')/items?$select=ID,Modified,Application_x0020_Status1,Title

But if I added a column that comes from the site content type, for example Description, this column fails to appear in my data source (although no error occurs)

I have tried other ways to obtain the data, but I'm limited because I'm connecting to XML Form Libraries which Power BI doesn't support, and the libraries contain many lookup columns which means other methods fail due to the lookup threshold.

How can I include columns from both the XML forms library, and from the site content types, into the same data source in Power BI?