Siri won’t read calendar when locked

When my phone (iPhone 11, iOS 15.6.1) is locked, Siri will not read my calendar. Rather, Siri will tell me to unlock my iPhone first. This is incredibly inconvenient and defeats the purpose as sometimes I'm driving and want to ask Siri when my next appointment is. Anyone have any advice?

I've tried:

1. Updating phone
2. Resetting
3. Adjusting every possible permutation of settings in both Siri, Accessibility and Calendar.

I've looked everywhere online and haven't found a solution. Any help would be great appreciated! Thank you!