V7.x to v8.x update causes MvvmCross.Exceptions.MvxIoCResolveException on release build 
## 🔙 Regression

### Old (and correct) behavior
App runs in both Release and Debug modes and the VisibilityConverter is used.

### Current behavior
An exception(MvvmCross.Exceptions.MvxIoCResolveException) is thrown when running in Release mode and the VisibilityConverter is used.

### Reproduction steps
Here is a repo of the TipCalc with the problem.
https://github.com/LeeTheGeek75/TipCalc

To reproduce I added a second View and ViewModel with a TextBlock and a button. 
Added the Visibility Converter.
Bound a property to the visibility property on the TextBlock.
The button then sets the Visibility.

In VS run the solution in Release mode and press the button.

Note: if the solution is run in Debug it works fine.
If I've missed anything please let me know.

**Version:** 8.x

**Platform:** 
- [ ] :iphone: iOS
- [ ] :robot: Android
- [ ] :checkered_flag: WPF
- [X] :earth_americas: UWP
- [ ] :apple: MacOS
- [ ] :tv: tvOS
- [ ] :monkey: Xamarin.Forms
