Change in reusing visuals in different threads?

[wstaelens]

We have a situation where we have XPS documents being created.
Each XPS documents is handled in their own thread.
No problem here so far.

Each XPS document adds a Visual to their document.
It is the same visual.

This works but is slow when processing a lot of files as we need to create the Visual each time again per XPS document.
(let's say 10.000 times).

Instead we added a MemoryCache where we store the Visual serialized.

Retrieving the Visual from MemoryCache is where we "reset" it by deserializing it back to a Visual and then setting the FixedPage "ChangeLogicalParent" to null.
This allows us to use the Visual on a different thread.

result.GetType().InvokeMember("ChangeLogicalParent", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.InvokeMethod, null, result, new object[1] { null });

This all worked fine, but since a few weeks this "trick" that allows us to "detach/reset" a Visual and cache it so it can be used by another thread has stopped working and thus the complete caching doesn't work anymore.

Now it gives:

The calling thread cannot access this object because a different thread owns it.
at System.Windows.Threading.Dispatcher.VerifyAccess()
   at System.Windows.Media.DrawingVisual.GetDrawing()
...

We are not sure if this is related to
https://support.microsoft.com/en-us/topic/kb5022083-change-in-how-wpf-based-applications-render-xps-documents-a4ae4fa4-bc58-4c37-acdd-5eebc4e34556

The question:

Why does setting "ChangeLogicalParent" to null not work anymore? What broke it? And what is now the "new" way of getting this same result?