Xamarin Forms button rendering in grids on WP

I'm currently experiencing an issue when i try adding a button into grid on WP.
It seems the button renders with a margin which end up making the button smaller then it should be.

I initially thought this was a WP issue and decided to recreate the entire ViewCell in a plan WP Silverlight 8.1 project.
This lead me to create a render for WP to override the default margin WP adds to buttons, but this doesnt seems to work on Xamarin.

Would anyone be able to tell me why or give advice on where i could look to resolve this.

I've attached the renders of both projects, hope that helps.