Screen Space Overlay canvas prefab becomes unclickable

First, this issue only happens when working with multiple scenes.

I have a Screen Space Overlay canvas thats part of a prefab I use in all my scenes for a consistent overlay menu. In the scene I create the prefab in, everything works as expected. (mouse over, click, etc)

After I apply my changes to the prefab and go to another scene with it in, none of my mouse over or clicks on the previously working menu work anymore. thought if I create a new overlay canvas in that scene, or in runtime, and move the children to it, everything starts working again.

This have been driving me crazy for weeks, as I can’t see why this behaviour is happening.

Relevant packages I’m using that could have an effect: SteamVR, VRTK

Any Ideas?

I was missing an eventsystem. added that to the prefab and all the scenes are good now.