One upon a time, there was a University whose administration was enthralled by a religion called Canvas. The central tenets of Canvas were held in the highest esteem and those who followed Canvasitic doctrine were expected to prepare their course materials through prescribed rituals and incantations.

When preparing the course, problems for homeworks and quizzes (assessments) could be organized into Question Banks stored in the professor’s office.

• To create an assessment, a special place was prepared on the wall of the classroom.
• The professor would photocopy the Questions from the Question Bank, one for each student, and would post them in sheaves on the wall for the students to take.
• The students would collect the assessment. When they completed it, the scores would be tallied and magically stored in the Professor’s ledger.
• The go-getting-est among them would realize some error or typo on a Question and inform the professor.
  Even though the professor could alter the Question in the Question Bank, the photocopies had been made and he could not alter the Questions already taken by the students.
• However, he could amend the photocopies on the wall for those laggards who had not collected their assessment from the wall. For those students, the Question was corrected.
• The amended Question was only corrected on those assessments left on the wall. Harried for time, they (the professor) may or may not have corrected the Question in the Question Bank. This will be important later.
• The laggards would have correct tallies but the go-getters’ tallies had to be manually amended, one by one.

At the start of the next year, the professor, exhausted, asked “can I not reuse the materials from last year?” The high priests of Canvas exclaimed “but of course!” in a tone that suggested the professor was interested in mustard of Francophone origin. The professor chanted the strange rituals and lo and behold, a copy of the class was prepared.

For each section of wall (assessment), sheaves of amended Problems were already there, rustling in the autumnal breeze.

• The amended Problems did not appear in the Question Banks. The magic of Canvas was unable to “scan” a problem from the wall and copy it into a Question Bank. It was as if the Question on the assessment was an entirely different object from the Question in the Question Bank.
• The professor, full of great plans for improved assessments, began to amend the Question Banks. However, since photocopies had been made, so the professor tore down the sheaves of Problems on the wall and prepared to make a fresh batch of photocopies.
• However, the magic of Canvas had also created phantom duplicates of the Question Banks in the professor’s office, so the amended Questions and unamended Questions were hard to distinguish. Moreover, problems with editable equations were copied as uneditable photographs (PNGs).

The professor, distraught, turned to their local priest. The priest, unable to help, conveyed the question to higher authorities, where it vanished.

Meanwhile, the professor’s assistants waited for some instruction on how to prepare the course for the hundreds of students already waiting outside the classroom…

[NB: as afar as I can tell from searching forums and documentation, this is actually how Canvas behaves, but I am willing to be shown otherwise.]