Pete.Green • Adobe Employee, Nov 14, 2018Nov 14, 2018
After a chat with one of the engineers, it looks like this one is working as designed.
The changes made to the Adjustment Layer get recorded in the Action when you select either the same layer, or another layer in the Layers Panel. This is probably to reduce the amount of changes made/steps recorded to the action.
I'll close this report for now. Let us know if you run into any other strange behavior!