I did more investigation on the bindings (duh, only two months later). It turns out the bindings are replaced when the value of the target dependency property is replaced. This has some logic to it, as in XAML we write

<MyObject MyProperty="{Binding SomePath}">

and thus the binding becomes a “value” of the property, at least visually. Thus, if we now have MyProperty=”42″, the bindings should go. However, this seems to be catching even some Microsoft developers by surprise (Google “radio button binding bug”).

I could not reproduce binding disappearance after converter failure (converter throws exception), either one way or two way. This was probably a quirk of our specific program, or some other, unrelated problem.

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