Ok, I'm back with more mysteries. I'm having things disappear—quizzes and pages to be specific. Using the www.school.edu/coursename/undelete trick didn't work for me. I always save and/or publish things so that's not it, but there are two things that could be contributing to the phenomenon: 1) I am working collaboratively with another teacher and we are often working in the course at the same time. 2) I also often have more than one Canvas tab open with my course in it. Both of these have been the case for more than a month but it's only recently that things have started to disappear.
Any ideas, oh gurus of Canvas?