App crashes after installing a Xamarin-Forms app

I have 3 self-written apps on my phone. 2 written with Xamarin.Android and one written with Xamarin.Forms. But there is a big problem. It always work only 2 or 1 app depending on which of the 3 apps was installed last. If one of the two Xamarin.Android apps was installed last, then both Android apps work. The Forms App, however, crashes immediately. Just the other way around. If the Forms app was installed last, it works fine. The two Android apps crash immediately.

Is there any reason for that? Are the frameworks not compatible?