If the customer/user is using a dark mode (contrast themes) different to the default selection via Personalization ==> Themes that might create problems with the PDF file generation on Cloud V 2.0. One customer so far reported this issue trying to generate a shipping slip but it might be a problem for other parts of the POS. 

If the PDF generated looks like this, then the problem is associated to Windows contrast themes 

To fix it

Just go to Personalization ==> Themes and choose a different theme, a theme with no dark mode is recommended