I recently added 7 students to my course, which we've been using since 2107. Three received the invitation and successfully joined the course. The remaining four have not received the invitation email. (I have confirmed email addresses and they've checked their spam/junk folders.) In attempting to resend the invitations, I receive a notice confirming that the person was added to the course, but that the invitations aren't sent until the course is published. (Emphasis in pop-up, not mine.) However, the course is published per my dashboard and six years of use. 

My organization only supports the institution Instructure courses and can't really help with canvas.instructure courses.

I appreciate any assistance in getting these invitations sent so that they can join and access content.

Thanks!