@Pauiel No, pregunta is not masculine, and wasn't show as masculine in any Duo exercises.
Una pregunta, la pregunta.
You probably confuse with "problema" that is an exception-word.
It looks like a feminine word (99% of the time, words ending with "a" are feminine, but no luck: this is an exception)
So: un problema, el problema.
"Question" in English has 2 meanings:
- asking a question (= pregunta)
- a point/a dispute/a issue (= asunto, tema, cuestión)
But "pregunta" is not a point, I can't find it in any dictionaries.
You should make a screenshot, and send them a bug report with a link toward a Spanish dictionary, like the RAE. I don't see other way to ask them to fix that.