I'm a site admin for a Moodle site running version 3.5. The version of the Questionnaire plugin I use is 3.5.14, which I believe is the final release for Moodle 3.5.
I noticed something strange today: the "View All Responses" link had disappeared in all the Questionnaire instances across all the courses on my site. I checked the permissions and then checked the Logs to see if any other site admin had done something unusual, but I couldn't find anything out of the ordinary. Just a week back I had viewed and downloaded the responses from a Questionnaire, and since then there have been no upgrades or any maintenance work.
I started to post a query here and I decided to explore the Logs a little further. I clicked on a log entry from last month where another site admin had downloaded responses from a Questionnaire, and I could see the "View All Responses" link for that particular Questionnaire. And one by one, as I refreshed the other Questionnaire pages where this link had been invisible, I could see the link again!
So now my query has turned into a sort of incident report. The "View All Responses" link mysteriously disappeared for a few hours, and it came back just as mysteriously, though at least I can say that I was witness to the latter 🤔