When you put multiple sub-tags under the items tag of an advancement JSON file, it won't work. For example, if you put two sub-tags under the items tag, the game doesn't accept it.
What I expect to happen:
The game will accept both of the sub-tags.
What happened:
It didn't.
If you didn't understand my explanation, please refer to the attached JSON code.
That advancement does work and ought to be given to you once you have both logs in your inventory.
If you want it to trigger only when you have either log type in your inventory, you'll need to move one to a different criteria and customize the "requirements" setup.