Could not link assemblies, Object Reference not set to an instance of an object, Release build

hi,

I am trying to build in release mode to publish my app on app store,
but the following problem happened,

Could not link assemblies, Object Reference not set to an instance of an object, Release build

I am using xamarin.forms 2.5.0.121934
Xamarin.ios 11.6.1.2

after googling it, the problem may be a bug in MTouch

any ideas?