xaml - Why would Xamarin Forms Activity Indicator not be rendered on iOS? -

i using xamarin forms 2.3.2.127 development of mobile application.

i have activity indicator sits within stacklayout, in turn contained within grid row.

the activity indicator renders on android, not render on ios.

the controls xaml follows:

<activityindicator widthrequest="50" color="red" heightrequest="50" verticaloptions="center" isvisible="true" isrunning="true"/> 

there no bindings applied @ present, , there have been no changes underlying control using customrenderers.

any ideas on causing issue, or if there common bugs? has occured before in other projects , rectified without changes randomly.

i had same problem & not visible during operation, m using mvvm binding, solved invoking mainthread

xaml

<activityindicator isvisible="{binding pbvisibility}" isrunning="{binding pbrunning}" color="black" /> 

viewmodel

 device.begininvokeonmainthread (() => {                     pbvisibility = true;                     pbrunning = true;                     raisepropertychanged ("pbvisibility");                     raisepropertychanged ("pbrunning");                  }); 

you run in mainthread & work.