Is this the right place to ask this question? If not, please tell me where to go <grins>.

I use 2 Android devices Samsung Galaxy S7 Edge running Android 8.0.0 and Samsung Galaxy Tab E running Android 7.1.1. Both of them work the same in regards my question.

I have configured Google Play > Settings > Auto-update apps = Auto-update apps over WiFi only. Please don't bother with any comments on the desirability of it being set this way!

But it doesn't seem to work in the way the words suggest. Every time I go look at Google Play > My Apps and Games it shows:
Updates pending (#)
Auto-update is turned on

And I have to tell it to update all, at which point it downloads the updates and installs them.

I had expected that an auto-update feature, when enabled, would at least download and probably also install updates whenever they were available.
I'm not talking about updates to Android, just updates to the apps I have installed.

What am I missing?