Annotate student work on an Assignment

[HopeM]

I have the Teacher Canvas app on my iPad. 

Last year, I was able to annotate student work with my Apple Pencil on uploaded student work. 

This year, however, when I click on the Assignment, I am unable to annotate the assignment. I can still assign a grade but I want to be able to indicate to the student where the errors are and how to fix them. 

I have tried opening Canvas on the Safari internet browser and am able to do some annotation but it is much clunkier than last spring. I have also tried downloading the file from Canvas and grading it but the file that I downloaded was empty, even though the original file was not. 

Any advice on how to annotate student work in the Canvas Teacher App? 

Thanks, 

Hope