Hi @TrevorFraser ...
I cannot be completely sure, but it looks like your screenshot *might* be on the "Modules" page of your course? If so, I am not able to replicate this issue on my end. When I click on the three dots next to a module item name and select the "Move to..." option, a slide-out menu appears on the right side of my screen, and I am able to move it to whever I need to within the course.
Have you tried reaching out to Canvas Support to see if they can help troubleshoot this further? Click on the "Help" button in your far left-hand side global navigation menu, and then select "Report a Problem". Be sure that you are viewing the screen where the issue is occurring before you click on "Help", as this will send some metadata along with the ticket you submit. How do I get help with Canvas?
Good luck, and keep us posted once you hear back and *hopefully* find a solution.