Just add the folder where the trainers are and the trainer itself to the exclusion list and that should do it. Sometimes Defender loves to act up.
That's the crazy thing. I added the trainer to the exclusion and when I opened it up, defender decided to act funny again. I just turned real time off while using the trainer. It's not too much of a headache.
It is weird, but I faced some issues with Defender as well in the past. Regardless of that, whenever I did face these issues, it went away by itself after a while.