SearchView in OptionsMenu not full width

Question

I have a working SearchView which expands in my OptionsMenu when the user taps on the search icon. However it only expands within the available space among the other Option

Answer 1

As crazy as it might seem, in my case problem was this line: app:actionViewClass="android.widget.SearchView" in menu.xml:

When I removed app:actionViewClass, it fully expanded as defined in my layout_search file.