Office Lens is incompatible with Adobe Acrobat
It is not possible to generate valid PDFs in Office Lens if Adobe's Acrobat Reader app is installed. Lens will generate invalid files that cannot be opened in any PDF viewer. Once Acrobat is uninstalled, everything works as expected.
Acrobat is, far and away, the most used PDF app in the world. I actually depend on Acrobat's functionality so this incompatibility is a significant problem. Due to their relative user bases, this should be classified as a defect in Office Lens, even if Acrobat is doing something that broke Office Lens's normal functionality.