You should get this when trying to load a layout on a panel without giving it a size with SetLayout before.
But sometimes layout size can be dynamic, so it can be normal to load the layout and then giving the panel the correct size checking the content.
If everything is working correctly I would not give it too much attention.
Anyway to solve this it should be enough to add a Panel.SetLayout with some dimensions before loading the layout.
Then probably you have already another SetLayout immediately after that will resize it correctly.
If instead your panels have a fixed and certain size, set it before loading layout.