Problems with render priority in UI Canvas


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As you can see on the GIF, I’m having problems with the render order.
I have an interactable button that needs to be seen (obviously :p) but a lot of other sprites have more render priority. I have no idea what’s happening.
I have tried with layers and Z positions. But nothing helped.

Other info
Unity version: 2018.2.3f (but this happened me with older versions)

All the sprites (except from the blue map in the background) are inside a Canvas. This canvas is in “Screen Space - Camera” render mode. In other render modes this problem happens too. Is a 2D game and the camera is in orthografic view

Thank you

The render order of UI elements should (almost) never be done by z-sorting. Instead, you should change the order of the objects in your hierarchy view. The lower the object in the hierarchy, the later it will be rendered (so the opposite of Photoshop Layers)

I tried too. But it doesn’t work.
I have tried to change the order in the hierarchy, but I haven’t seen any change.