I have a similar problem. Several days ago, I asked Siri what was on my calendar next week. She promptly responded with a list of appointments by date and time. However, this morning when I asked what was on my calendar this week, Siri responded with the following question: “What shall I set it to?” I tried making my request in various ways: “What is on my calendar this week (or today)?” “What events are on my calendar this week (or today)?” “Is there anything on my calendar this week (or today)?” All of my requests elicited the same response from Siri: “What shall I set it to?”
Through trial and error I determined that the “it” Siri was referring to were four alarms that I previously had set. (For example, “Siri, set an alarm for 7:00 tomorrow morning.”) I deleted them; however, Siri still will not inform me of calendar items. I have not added, deleted, or updated any software, apps, or settings between now and last week. Nor have I changed any devices such as my iPhone or iPad.