Since the 2/25/21 update to the ios Canvas Teacher app, I'm having the following problems when grading on an iPad with an iPencil:
1) I can no longer swipe between submissions of an assignment if I have made comments on that assignment. I have to go back to the assignment each time to access another student's submission.
2) If there are multiple file submissions uploaded onto an assignment, I can make comments only on the first of the file submissions. The menu where I would select an annotation method doesn't activate at all on the other files..
For problem 2, try to click "comment" instead of "files", you can see the uploaded files in "comment". You can make annotation on all the files found in "comment". I've just found it out!
As for #1, this feature is still available for the iPhone, so my assumption is there is an issue with the iPad version preventing the swipe action and it will be brought back in a future update. If I find anything out, I'll post back here.