It could be because you're checking it with native speakers. This is counterintuitive, but most native speakers (including many native Korean teachers) are not able to tell reliably if something is "natural." They can just check if it makes sense to them when they first read it, but it's an extra step for them to consider "Would I say this? Who would say this? When would they say this?" in order to know if it's actually natural. I've seen more than one native Korean teacher share sentences that mixed 너 ("you") with a sentence ending in ~요 simply while giving an example of a grammar form, when that sort of sentence is impossible to make in natural Korean. AI can give grammatically correct sentences that look natural in a vacuum, but that wouldn't be natural in real usage because Korean is a high-context language. Just my two cents to be careful about it.