Why is there an option to select all my students when it seems that I can only send reports on about 5-10 at a time? It requires a lot of checking and unchecking of boxes. Any way to fix this?

When I import a class from Google Classroom, all my students appear, but there are no guardians listed. Also, in the "send email to" drop-down menu, the only option is "students". When I check "include guardians" on the import screen, nothing seems to change. I need to share students' grade with their families. Help!