When a custom theme is used that includes a custom font family in the desktop edition, clicking on the PDF button sends you back to the Businesses page. No PDF is generated. Reverting to any of the built-in themes allows a PDF to be generated. In the cloud edition, the same custom theme presents no obstacle; a PDF is generated and downloaded.
I’m removing this topic from bugs category on the basis that this issue is in internal PDF generator which is now obsolete.
There is now new approach which doesn’t have this issue. So if you are affected, I recommend using the new approach.