Black Screen for 15 seconds before loading the Root level

Right now I have a video that starts playing a logo animation that takes 12 secs. Then I have a Root level which contains two sublevels, one Loading Screen and another level with a MainMenuScene I made. As someone suggested me, I created a Print String node inside Root BeginPlay and a second Print String node inside the first level the game loads, which is the Loading Screen, linked to BeingPlay.

I got this: My initial intro video with my logo starts playing and ends after 12 seconds, then I got a black screen for 15 seconds and then finally loads the Root level and sublevels so both Print Strings appears at the same time.

For an unknown reason, takes 15 seconds to start loading the levels.
What can make a game freezes that time before Root?
What could be the problem?
Which things can I check?

Thank u!

i guess you could load the level initially and then just play the animation on top of it with a widget? this way you could avoid the loading times

Okey, I get this black screen from Editor using Standalone mode but If I package the project, it just works fine playing the intro video and once its finished, loads Root level while MainMenu is loading so both Print Strings gets activated almost at the same time.

So for me it works now.
Thnx anyway

Can you elaborate your answer? I have same issue but unable to understand your answer

What I said was that I had that problem only when I use Standalone mode from Editor.

If I package the game for developement, doesnt take that time and my loading screen appears while Main Menu is being loaded