Instructor here. I do not have a problem with adding a Google Drawing assignment (unless I forget to put anything on there...) nor students having problems submitting the assignment.
When submitting, Google Drawings becomes a .pdf file. My issue is this: Sometimes I am lucky to see the whole document (second picture), most of the time, I see a certain percentage of the document (first picture).
It seems that Drawings automatically become a PDF for Canvas, to save memory/space, which I understand completely, but have yet to figure out why some students (pictures are from the same assignment) show full or partial. I thought maybe it was a zoom thing, apparently as a student attempted to submit assignment again with that adjustment, that it is not the issue.
I suspect it is from the student's side but I cannot experiment on my own (as a student) to figure out what it is. Thanks!