When I use the built-in add extension I need to manually initialize it by script with:
Advertisement.Initialize(gameID,…)
else Advertisement.IsReady() is allways false.
It was not necessary withUnityAds 2.X…
Is it a bug? or is it the normal behaviour from now on?
I believe this is behavior that was added recently to make the Asset Store Package and the Services Window behavior more consistent.
You should be able to find your game IDs in the Operate dashboard:
https://operate.dashboard.unity3d.com/