IOS 14: daily automation not running

I have set up a simple automation to run a Shortcut at 6am every morning. If I test the shortcut, it works. If I set the time for [10 mins from now], it works.

However, it never seems to run for 6am where:

• The phone is plugged into power
• The phone is on WiFi
• The phone is in Do Not Disturb
• The phone hasn’t been unlocked since I went to bed (11pm ish)

I don’t think the power/WiFi/DND make any difference but is there something in iOS that stops automations running if the phone hasn’t been unlocked or used for some period of time?

I see exactly the same issue with a totally different automation that’s supposed to run on my iPad … it runs about once per month if I am lucky and I am wondering if those are times when I had used the iPad in the past hour or so.

Is this a bug or is there something that stops daily automations that I’ve missed in the documentation?

Update – here’s how I created it: