Hi there, @baldwinsh ...
I'm not sure if you are a Canvas administrator or not, but there is a recent thing that some of us have discovered related to two Feature Options that can be toggled on/off. One is "Assignment Enhancements - Student", and the other is "Enhanced Rubrics". If "Assignment Enhancements - Student" is disabled but the "Enhanced Rubrics" Feature Option is enabled, then you're going to get the results that you mentioned. However, if both of these Feature Options are enabled, then students will see the attached rubric.
I submitted a ticket about this yesterday (because I thought this might be a bug), so they are aware of the issue. As for their plans on a possible fix, I'm not exactly sure of that...or if this was intended behavior with these Feature Options.
If you are not a Canvas administrator at your school, I'd suggest that you reach out to your Canvas admin at your school or someone from your school's Online Learning / eLearning / Distance Education team. They would be able to tell you what they have set at the account level.
I hope this will be helpful in some way.