Why is there a black square with my flipbook?

Game - 2D platformer
First time using UE4

So I have been tasked to create a basic platformer game as a project for my university work. When I created my animations using the photoshop and after effects, I noticed that I had a black square that was in the background of my frames, so when I created the flipbook and added the animation to the game there was a black square that surrounded the animation.

What I did

  1. imported the .tga files into UE4


  1. Then I applied the paper 2d texture settings and created a sprite of each frame.


  1. Then I took the sprites and then created a flipbook with them.


  1. I then applied the new flipbook for my main character.


This is how it looks within after effects


I managed to fix this by exporting the sort animation as a PNG Sequence on After Effects.