There is a problem that occurs with the layout persistence of the XamDockManager when the TabGroupPane has a name. If LoadLayout is called and it makes all panes be undocked (I had two panes), redocking the panes in the center of the DocumentContentHost makes them completely disappear.
I'm using v9.2.
I've written a simple app that demonstrates the problem.
1. Click on "Open,"
2. When the child window opens, drag both the content panes so that they are floating.
3. Close the child window.
4. Click on "Open" again.
5. Try to dock one of the floating panes in the CENTER of the dockManager, it will disappear.
Now that it is proven that they do indeed disappear, try the following:
6. Remove the name attribute of the TabGroupPane.
7. Repeat steps 1 - 5.
It will work normally now.
What version are you using? Also, if you can provide a sample that demonstrates the problem we can look into the issue.