Student here but I went through the Canvas help (done through my university and they didn't have a fix). 

Copy/Paste not working in Canvas specifically for the feedback/comment box in Chrome. Doesn't allow for any action other than typing and when you attempt to paste something (like a zoom link) using shortcut keys first nothing shows up then if you go into a word doc/other program and paste the below error pastes rather than what was originally copied. 

"Sorry, no manipulations with clipboard allowed"

Have tried in other browsers and only have this issue in Chrome. Never had this issue until now (prior semesters there was never any problem).