I am running the Canvas Teacher App on an iPad Air (3rd Gen) with iOS 15.4.1. I am a professor and I have been using the Canvas Teacher App on this iPad/pencil (earlier versions of iOS) for at least four years. For the past several years, I have been able to annotate submitted PDF files for assignments by using my iPad with Apple Pencil.  However, I am discovering this semester that when I open an assignment and try to grade it, if the assignment has a Rubric assigned to it, then I am often completely unable to make any annotations to the submitted work.   Sometimes the student's assignment will open with both the rubric and the annotation bar at the top. However, most of the time, after the PDF file loads, there is NO OPTION for making any annotations on the submitted PDF files. NOTHING at all -- no pen selection, nothing. This seems to happen most frequently when a PDF file takes a long time to load -- but once the file loads with no annotation bar, swiping to another student assignment also has no annotation bar, regardless of how quickly that next student file opens.  Sometimes, if I open a new assignment, then the annotation bar will appear for a couple of students, but then if I swipe to another student whose file take a few seconds to load, the annotation bar disappears and I cannot make any annotations for any other student in that assignment. And once the annotation bar has disappeared, I cannot get it back for any other submissions for that assignment, even when swiping through all of the other student submissions. This is becoming extremely frustrating as I am unable to grade any assignments for my classes using the same tool that I have been using for several years.

I have attached two screen grabs -- one with showing the rubric and the annotation bar at the top, and the very next student (after swiping) for which the annotation bar has disappeared.

To forestall the typical IT responses . . . yes, I have uninstalled and re-installed the app and that does not fix the problem.  Yes, I can annotate