Yes, it's true you won't have a problem. I've also flown EY without inputting my middle name in the record. That said, I was given some good advice recently when booking flights on Asian carriers (especially CX) recently. I know CX wants it to match exactly. So when they ask for first or "given" names: input both first AND middle name in the field with a space in between. I've been doing that without issues after having a few problems checking in with CX and another carrier I can't remember in the past...