I had the same issue, turns out it was my resolution/scale on my monitor. I'm using a laptop and tv as my main monitor and trainer would work just UI was totally blank. Changed my scale to 100% & restarted my pc and trainer works fine now, UI is there and all the trainer functions.
Press escape in the game.
i had the same problem, trainer starts up then dissappears , in my case it had to do with msi afterburner, if i disable msi afterburner first then the trainer starts up normally, and running msi afterburner again doesn't close the trainer, no idea about the why though.