PDF as document content type in document set - no metadata

Hello

I have a templates library, each template has DocumentType metadata.

I have a document content type called 'Speaker Author Agreement Recording'. It is a PDF. In its advanced settings, it links to the Speaker Author Agreement Recording template in the template library and its metadata.

I have a document set called 'Webinar' that includes the Speaker Author Agreement Recording document content type. I include it as Default content and the name of the doc set is added to each file name.

When I create a document set in a library, it imports the Speaker Author Agreement Recording template but does not assign its DocumentType.

It works for the excel and MS Word documents. It does not work for the PDF document. 

Can you please tell me how to fix this. Thank you :)