I have problems with an WMS laye, its shown perfectly on iOS and Windows, but not on Android...
I can send you by mail, if you provide it to me, the URL and the layers to show if you cant provide me information with this simple description.
Is this reproducible using our simple WMS Layer sample? What model/make of Android device? What version of Android OS? Is this issue using built app or using AppStudio Player?
You can share and work with our Esri Technical Support, they have AppStudio experts who can help you troubleshoot this issue. https://support.esri.com/en