ImageButton Source property not updating

Hello everyone,

I am new to Xamarin Forms and this is the first time I post here.

I am currently developing a minesweeper in Xamarin Forms and I ran into the following issue: when I change the value of Source of a ImageButton inherited custom class, the UI won't update the image.

I used the debugger to see the value of "bc.Source" after the call, it is well set to "2.png" which should draw another kind of cell.
I also viewed the value of the buttonCell inside the Grid Layout and the "Source" property is "2.png" (previously "untouched.png") which should draw another kind of cell on the grid.

I really don't understand why the button image won't change its drawing.

Thanks everyone