Yep, I can attest to this. Happened to me back in January. I could have sworn that I did fill in my full name including the middle name, but what happened apparently is after I manually filled the form in, there was a machine reader step when I uploaded the picture of my passport, and it overwrote what I had filled in manually. Now that machine reader failed to capture my middle name, hence the application was deemed deficient and was denied. I ended up having to spent an extra two weeks outside of Thailand because I had to redo the application all over again. Not fun at all.