Safari not exporting as PDF after sleep / user switching

OSX 10.15.1

After a period of sleep, or after user switch, Safari no longer exports as PDF claiming the destination folder (or even desktop) can't be opened.

Print, then save as pdf, seems to work as it gives no error message, but the PDF files are never "printed".

Relaunching Safari and/or Finder doesn't sort it.

Works again after reboot.