When Printing a PDF, default paper is set to "Heavy Weight"

Client has a problem when trying to print any PDF document from Acrobat DC Standard; the paper type is set to "Heavy Weight" paper.

This causes the job to stall when printing to their Xerox Color Cube 9301 PS, since this is not a paper type that is loaded.

The client can change the paper type prior to printing, but we'd like to find out why it doesn't just default to plain paper.

The problem only occurs with PDFs; word documents print on the correct paper.

Tried taking a copy of an offending PDF and opening it on other computers; the paper type selected is plain paper.

Checked the driver settings on the user's computer and the server; Plain Paper is the default.

Client is running Windows 10 Pro 1511

Any ideas as to why this is happening?

Thanks,

Lou