You are correct that most questions on power assertions here relate to sleep and not the [screen saver][1]. You can use those answers to get started, but focus on the **UserIsActive** assertions and text. 

Here is a way to cut through the noise:

    pmset -g assertions | grep UserIsActive

Your item is currently **product:Magic Keyboard with Numeric Keypad eventType:3**. 

You should be able to test this quickly by disconnecting it and waiting the two minutes. If you are very curious you can also watch the log as you wait the 2 minutes:

    pmset -g assertionslog


I would change all your sleep settings a bit if you don't see the UI matching what you have.

[![Lock Screen Settings][2]][2]

Maybe make sleep never or an hour - add a minute or 5 to the password and display off setting and bump the inactive up or down 1 minute and retest.


  [1]: https://apple.stackexchange.com/q/472555/5472
  [2]: https://i.sstatic.net/XIyhOdwc.png