I haven’t read your last answer yet
But I wanted to share some tests that I did on my side to solve the problem: the Asset Status
To be sure that the problem could come from our assets
I deleted all the audio and their audio player from the project
I also deleted all the textures except for the one attached which has as texture group: UI
And as compression setting: UserInterface2d(RGBA8)
I also after all that regenerated the HLOD file as explained in the previous post
Despite all that I had the same problem with the test
PS: If the image is not visible it is normal its alpha is at 0, its dimensions are 256X256