What could make the depth and AO passes blank in Eevee?

I had AO pass working in the rendered viewport preview before, selected from the drop down list here:


But now when I try, it’s suddenly just blank, both in the preview and in the final render pass?

Anyone know what setting I’ve apparently accidentally touched to cause this?

Without a Scene its difficult to say, but I will guess that you didn’t activate AO in the render settings.
And the depth pass gives you a gradient not normalized, so at 0 meters it will give you black, and white anything above 1 meter will show completely white. You can plug a Map Range node in the compositor if you can see the result.

English is not my first language

No worries. I mentioned AO was working in the viewport before, regardless of the render pass setting. But turns out, it was a temporary bug… now, suddenly it is working again!

I didn’t change anything this time either, so no idea what made it stop, and start working.