Check out this page; I just learned new stuff by reading it https://community.canvaslms.com/docs/DOC-16571-4152813670 Apparently if you use the Hide Grades link it ONLY affects already posted grades. So if you add more grades for other students after clicking that they are not hidden. Totally not what I expected. The document suggests if you are wanting to hide grades before entering them that you should instead use a Posting Policy to control when students get to see them. I won't lie; I'm bitter about this works (#BringBackMute/UnMute) but I hope the information on that page helps.