Debugging Xamarin.iOS crashing app with error: * Assertion condition `!tls’ not met

Ι get intermittent crashes with xamarin iOS app while debugging on physical device with the following error

error: * Assertion at /Users/builder/data/lanes/5909/60a17f1c/source/xamarin- macios/external/mono/mono/mini/debugger-agent.c:3901, condition `!tls' not met

i am using

Visual Studio Enterprise 2017 for Mac
Version 7.6.11 (build 9)
Runtime:Mono 5.16.0.221 (2018-06/b63e5378e38) (64-bit)
Apple Developer Tools
Xcode 9.2
Xamarin.iOS
Version: 11.6.99.33