Custom model issues

Schema has more than 40 fields and also using the [KeepCasing] attribute on the class. I have seen the given link and saw only one change and tried that also by making the properties from Localized to Dictionary<string, string> but same issue.

Any other thoughts?

Enclosing image if you see any thing in the trace and This issue is coming while posting the data on the Button submit.

It could be a data binding issue. Why is it even reading the app property?