Proofreading on iPad Pro and Apple Pencil, what works now?

Dear all,

My team used iPad Pro (the one before the new designed iPad Air) and Apple pencil to proofread an 80-page long document stored in the 'Files' system. Once it was done and 'Done' was clicked, all written comments were gone. The disappearance of the comments happened 3-4 times to the point that we could not work efficiently anymore.

Can any of you give me a solution to this problem? I've been reviewing the past conversations, and Notability was mentioned. I wonder if there're any other solutions to this.

I'd also like the Apple team to look into this. We were hoping that the device would give us a seamless workflow. But this kind of problem disrupted the workflow entirely. The proofreading had to be unnecessarily repeated again and again.

Best,

Chol