Strange problem with UI buttons after updating Unity

I have a problem with UI system after updating my project from Unity 5.1.4 to 5.6.4.The buttons don't work because they seem not to detect the mouse.
I have found the buttons do work when any input axis of keyboard (cursors keys or w,s,a,d keys) are pressed simultaneously !!
Very strange and very curious, because I have not changed my code and in Unity 5.1.4 the buttons worked well without this strange behaviour.

Any idea?

 

Though this should be unrelated to an update, just ensure that you have an EventSystem in your game.
Also, if your canvas is set to world or camera, make sure the right camera is referenced.

 

Thanks but it is not the problem.
As I said the code has not been changed and after the update all works well but the UI buttons.

 

Hm, k, sounds strange. Tough to imagine buttons not working in a release, but I haven't used every release
Hope you get it sorted.

 

Hi, we have experienced a similar problem. Since we came back from leave and the project we are busy with is now not functioning they way it was. We have a number of UI buttons that now for some reason default to a specific screen. Very peculiar. I think it has to do with the last upgrade as we have not touched any code. Anyone able to help. Else we will need to revert back to building buttons from scratch.

 

I've had reseted the layout to factory settings and worked for me...