Issue is that there is not two way data binding and I've made a simple radio button that does two-way data binding.
var _isChecked = false;
<label>
<RadioButton Name="radioExample" TItem="bool" @bind-Value="_isChecked" CheckedValue="true" /> On
</label>
<label>
<RadioButton Name="radioExample" TItem="bool" @bind-Value="_isChecked" CheckedValue="false" /> Off
</label>