PDF disappears when editing text box

I am using Xamarin and when I edit a text box the PDF disappears except for the highlight and the text of the box being edited.
https://drive.google.com/open?id=0B8ZD0BMqa0ANMXZxd0dOUmFSejA

Editing:
https://drive.google.com/open?id=0B8ZD0BMqa0ANYVFkVDRoZkJESzQ

How do I keep the rest of the PDF showing?

We couldn't replicate this with our PDFs, can you please send us the PDF?
Does this happen with certain devices or all?
Which version of the library are you using?
Does this happen with the demo project? or only yours?

This happens with all devices. I am using version 3.14. It does not seem to happen with the demo, just in this project that was handed over to us several months ago.

Was the project developed by your team?
Are you managing it but you're not the original development team?
Are you adopting our xamarin plugin from GitHub?
Are you building your own Xamarin plugin?

The project was started by another team. We are continuing to develop it. We've recently downloaded the Xamarin plugin from GitHub and purchased a premium licence.

The background does not just disappear. It actually fades out and when I click on the background again after editing the text in the field it fades back in.