Hi,
I'm using Moodle 3.7, and lately I encountered what seems to be a very disturbing problem with the "Annotate PDF" tool.
TL;DR
If a student uploads a submission (file) that the "Annotate PDF" tool can't view, and then uploads a submission that the tool can view, the updated submission won't be displayed in the tool and a never ending "Generating the PDF" message would appear on the screen.
More details
Someone opened issue MDL-65391 about this problem.
The original issue dealt with a more specific scenario, while the issue happens in a more general context, so I updated the issue with new information.
Could you please vote for this issue?
It doesn't seem to me like a minor issue. We already got user feedback from teachers about problematic submissions that can't be opened in the "Annotate PDF" tool.