The best workaround that I or the IT department could come up with is to give those assignments one point. Once they've transferred, I can adjust their point value back to zero in both Canvas and PowerSchool. As an added frustration, I can only do this for assignments where I have entered a students' grade, so I have to wait for a student to attempt an assignment before I can go through that convoluted process. I thought about making all bonus assignments out of one point and lowering the anchor grades by an equivalent amount, but that would require making students' assignment lists full of zeroes that they don't really have to do. Students and parents are confused enough by my system without me adding that kind of frustration to it.
This is the second program that I use for my classes that "upgraded" over the summer in a way that made them less functional and more frustrating. With the boys' sports schedules and this seven period day without the additional Friday prep time from last year, I was already struggling to stay ahead. I certainly didn't need this additional nonsense too.
That said, I'm still really liking the school year, my classes, and my students.