Why キログラム and not キロ here?
Because they wanted, but if you are writing and it doesn't accept it then report it
That's what i would like to know
牛肉を一キログラム下さい。I like the 肉 kanji don't leave it :３
Is キロ on its own not acceptable as kilogram? I could swear it accepted that in an earlier answer?
It is, and your memory isn't failing, it was te same sentence but with chicken
Can the ＂を＂ go after "牛肉ーキロをください"？
No, を generally goes after the noun and before the number/amount in cases like this.
ぎゅうにくを一キロください, was what i answered, Shouldn't it be accepted??
Wouldn't it be ''Hitotsu'' instead of ''ichi''? Or both are correct?
Only ichi. The ~つ in Hitotsu is used in counting physical things with a finite shape.
The の in this sentence was missing for me, had to use the keyboard
の is indeed used to link the counter and the noun when it is before the noun it modifies. however you don't need one if you place the counter after the noun and its particle.