Silence is information, not defiance.
When students go radio-silent, it tells you something broke. It could be technology barriers, unclear expectations, fear of looking stupid, or just that the activity has no clear purpose. This is especially true, depending on the generation. I've found that Gen X likes to get to the point. And to a Gen Z student, submitting a missing assignment IS communicating with the instructor.
The fix isn't nagging. It's consistent outreach to see what failed.