[iOS 12] App doesn't start when debugging (icon left greyed out)

### Steps to Reproduce

1. Create a new single view iOS app (using Xamarin's Xcode 10 beta 6 preview for VSMac)
2. Debug on simulator (I've repro'd on an iPhone X simulator running iOS 12, an iPhone 8 simulator running iOS 12, and an iPhone SE running iOS 12)
3. If the app launches successfully, stop the debugging session and delete the app manually
4. Debug app again
5. Sooner or later the app will get into a state where it is installed, but the icon is greyed out; the app never starts

### Expected Behavior

App should start and debug

### Actual Behavior

App does not start / debug. Icon is left greyed out.

### Environment

Visual Studio Enterprise 2017 for Mac
Version 7.6.1 (build 7)
Installation UUID: 623d8c09-02dc-4241-ad34-5c29ea2d12f7
Runtime:
Mono 5.12.0.305 (2018-02/e0e035e3b14) (64-bit)
GTK+ 2.24.23 (Raleigh theme)
Xamarin.Mac 4.4.1.178 (master / eeaeb7e6)

Package version: 512000305

NuGet
Version: 4.3.1.4445

.NET Core
Runtime: /usr/local/share/dotnet/dotnet
Runtime Versions:
2.1.2
2.1.1
2.0.5
2.0.3
SDK: /usr/local/share/dotnet/sdk/2.1.302/Sdks
SDK Versions:
2.1.302
2.1.301
2.1.4
2.0.3
MSBuild SDKs: /Library/Frameworks/Mono.framework/Versions/5.12.0/lib/mono/msbuild/15.0/bin/Sdks

Xamarin.Profiler
Version: 1.6.3
Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler

Apple Developer Tools
Xcode 10.0 (14320.12.2)
Build 10L232m

Xamarin.Mac
Version: 4.99.3.658 (Visual Studio Enterprise)
Hash: 1eefd4e3
Branch:
Build date: 2018-08-21 15:01:53-0400

Xamarin.iOS
Version: 11.99.3.538 (Visual Studio Enterprise)
Hash: 1eefd4e3
Branch: HEAD
Build date: 2018-08-21 15:01:52-0400

Xamarin.Android
Version: 9.0.0.18 (Visual Studio Enterprise)
Android SDK: /Users/bradumbaugh/Library/Developer/Xamarin/android-sdk-macosx
Supported Android versions:
2.3 (API level 10)
4.0.3 (API level 15)
4.2 (API level 17)
4.4 (API level 19)
5.0 (API level 21)
6.0 (API level 23)
7.0 (API level 24)
7.1 (API level 25)
8.1 (API level 27)

SDK Tools Version: 26.1.1
SDK Platform Tools Version: 28.0.0
SDK Build Tools Version: 28.0.0

Java SDK: /usr
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

Android Designer EPL code available here:
https://github.com/xamarin/AndroidDesigner.EPL

Xamarin Inspector
Version: 1.4.3
Hash: db27525
Branch: 1.4-release
Build date: Mon, 09 Jul 2018 21:20:18 GMT
Client compatibility: 1

Build Information
Release ID: 706010007
Git revision: 7c9e755fe667840f2eed42b2e7910ec18ef51b82
Build date: 2018-08-24 02:25:33+00
Build branch: release-7.6-xcode10
Xamarin extensions: 1196f085605a84ce99f390a1aaee0bf257d31a50

Operating System
Mac OS X 10.13.6
Darwin 17.7.0 Darwin Kernel Version 17.7.0
Thu Jun 21 22:53:14 PDT 2018
root:xnu-4570.71.2~1/RELEASE_X86_64 x86_64

Enabled user installed extensions
MonoGame Extension 3.7.0.1
Vim 0.61.0
Internet of Things (IoT) development (Preview) 7.5.3

### Build Logs

- IDE log after this happened with a new project:
[Ide.2018-08-28__15-57-46.log](https://github.com/xamarin/xamarin-macios/files/2329996/Ide.2018-08-28__15-57-46.log)

- IDE log (looks a little more helpful) after another project I have where I noticed this:
[Ide.log](https://github.com/xamarin/xamarin-macios/files/2329992/Ide.log)

### Example Project (If Possible)

I've been able to repeat this with a new iOS single view app