Silverlight: setting property directly removes data binding?

I am modifying a Silverlight project that heavily uses code to set properties, etc. This was created several years ago and is more or less ported from the WinForms project.

The problem I noticed is that when I set the data binding for the property, visibility in this case, if this property is set directly in the code behind, then the data binding is removed. I even set breakpoints in the PropertyChanged event to make sure this is the case.

I have done quite a bit of WPF development and have never noticed this. Is this normal and am I missing this or is something not quite right?