Unable to export - Blank Page

Hi,

My Export tool on Adobe Acrobat Reader DC has stopped working.   The rest of the program seems fine.

I click on Export PDF and it opens the relevant page, but it's blank rather than showing me the options it usually does.  It hasn't crashed, and I can go back and see the PDF/use the program normally.

Have tried restarting and still no luck, so any help you can give would be appreciated.