In Windows Phone 8.1 instance of my forms app, almost all of the controls have been set to null

My mainpage is an xaml based one and the android, ios, uwp and the windows 8.1 version of the same app all work normally.

However the in the case of the windows phone 8.1 version, almost all the variables referencing the controls of the mainpage are set to null.
I am using version 2.3.4.247 of Xamarin forms.

What could be causing the problem. The app was working previously.