Ok, I've tried to replicate and whilst the icons are not there, this is also true of other themes including core ones. Thus this is a functional difference between Moodle 3.4 and 3.5 and not a theme specific issue.
Re: [Campus Theme] Icons disappeared in Gradebook Setup after upgrade to Moodle v.3.5
د Gareth J Barnard لخوا -
د ځوابونو شمیر: 0