Regression or breaking change between beta 40 and beta 42

[Evangelink]

High-level description

I have noticed that I am starting to get some binding issues (stack trace below) when moving from beta 40 to beta 42.

Cannot get 'SelectedKeyFrame' value (type 'Object') from '' (type 'ViewModel`2'). BindingExpression:Path=SelectedKeyFrame; DataItem='ViewModel`2' (HashCode=9122323); target element is 'ListBox' (Name=''); target property is 'SelectedItem' (type 'Object') InvalidOperationException:'System.InvalidOperationException: Property path is not valid. 'System.Dynamic.DynamicObject+MetaDynamic' does not have a public property named 'Items'.
   at CallSite.Target(Closure , CallSite , Object )
   at MS.Internal.Data.PropertyPathWorker.GetValue(Object item, Int32 level)
   at MS.Internal.Data.PropertyPathWorker.RawValue(Int32 k)'

The property SelectedKeyFrame is bound to a subModelSelectedItem linked to a subModelSeq.

Steps to Reproduce

I am working on a minimal reproducer but thought it might be worth to open the ticket anyways as the "issue" is contained between 2 commits.

Additional Information
Elmish.WPF version: 4.0.0-beta-40
Target framework version: net48

[TysonMN]

Any progress on a production?

[Evangelink]

Hi @TysonMN! So sorry, I changed job and totally forgot about this open issue. I don't have the original source code obviously but I will try to see if I can still reproduce something locally (low chance).