Hello,
Thanks for answering me.
Like I said in my post, I can reproduce it in a clean project.
First I create a blank project, after I create a Widget Blueprint and import two textures.
I open my Widget Blueprint, drag and drop a Progress Bar from the Palette.
I set the Background Image and the Fill Image with my textures. I set them as Image in Draw As.
After that, I set the Percent in Progress to see the filling.
Then I set Bar Fill Type to Fill From Center.
I put a link of each steps if it helps.
Hope I was more explicit this time.
Have a nice day =).