Can I say it this way: "Ich will einen, bitte"
Last time I translated this "eins von jenen" was accepted. Now it's not. Does anyone know why?
I'd say forget about "jenen". It's rarely ever used. Usually, German speakers don't make a distinction between "this" and "that" or "these" and "those".
That's true, but duo is sometimes rather picky (and unfortunately very inconsistent) about it. BTW: Are you all right? You look very green (i.e. nearly as green as I) today ;-)
I could have sworn that two minutes ago I had a German>English question where I was asked to translate "Ich mochte eins von denen, bitte." Am I misremembering, or is that a valid alternate?
"Ich möchte" (note the Umlaut) is more like "I'd like". But maybe duo should accept it.