Searchview doesn't work since app compat

Try using the custom app namespace for your actionViewClass too:

app:actionViewClass="android.support.v7.widget.SearchView"/>

Add the following line to proguard-rules.pro file located inside app folder:

-keep class android.support.v7.widget.SearchView { *; }

This could also happen if you have proguard enabled and it is striping aways SearchView class. You would need to modify proguard settings to keep the class.

See this question for more details.