Red background when displaying PDF within image annotation

Title pretty much says it all.

I am creating a COTG form where I need to display the contents of a PDF document for annotation.
When I send the form to the COTG app and tap on the PDF, the annotation modal pops up but the background of the PDF is always red. I have tried using the standard ‘kitchen sink’ template to rule out my form and I observe the same behaviour.

I’m using Connect 2020.2.1 and my COTG client is version 2021.1 running on iOS.

Has anyone experienced similar?

CORRECTION
—> Version of Connect is 2020.2.1.

I’ve implemented a workaround by introducing an additional print template that lays the PDF on top of a white background. This isn’t ideal as it means pre-processing the PDF prior to running the COTG template, but it works.

I’d still be interested in a solution to the issue if one exists.