I can't see buttons in MaterialButtonToggleGroup

Question

I want to use the toggle button group to make it look like the picture below.

enter image description here

However, if I insert a button into the toggleButton Group, the size of the button becomes very small. Even if the absolute size is given to each layout, only the size of the toggle Button Group is enlarged and the button inside is small, so I can't see it. When you take out the button, it returns to its normal size and you can see it well, but it looks small only in the group. Can I know the reasons about this?