Files App Malfunctioning While Annotating PDFs with Apple Pencil on iPad Air

My iPad Air's one of the new gens, and I have the wireless changing Apple Pencil with it. Neither product is over a year old. I keep trying to annotate documents in PDF files with my Apple Pencil on my iPad but every time I reach a certain point, the document will "crash", and delete everything I've written for the past five minutes. This has occurred while writing, as soon as I stop writing, and seemingly at random. The file in on the iCloud Drive. Is this a bug in the Files app, iCloud or with my iPad? The only way to keep this from happening seems to be tapping "done" in the top right corner every three minutes to make sure my annotations save. I'd like to not have to use a third-party annotating software, mainly because its simpler and saves time (and sometimes money too). Is there a way to resolve this other than interrupting my work every three-five minutes?