UI not rendered while loading a Data Layer

Hello we are having this issue in our game. We have a UserWidget used as a loading screen displayed to hide level loading. At the same time we load a data layer: it seems that the fact that a data layer is loading is removing the entire UI (including the UserWidget we use as loading screen). This causes that for few frames the 3D world is shown.

Do you have any idea how to help out solving this issue?

Thanks

Dario