"I do not see food."
No, I used the appropriate accents. (The keyboard with special characters is not available on this comment page). It said it wanted me to use žrádlo but not jídlo....and that using jídlo was a spelling error... Either way, it seemed odd. I should have screen shot it.
BTW, is there a difference in your mind between "I don't see" and "I can't see"? Because "I can't see" certainly has more meaning than "I don't see". ("I can't see" implies there is some impediment, and "I don't see" does not imply anything). Is "nevidím" giving the sense of impediment (not able to see)?
Screenshot, or better just report as "My answer should be accepted." Anyway, probably Duolingo bug then, we can't do anything.
"Nevidím jídlo" is definitely an accepted translation, so... system grading bug at work.
I wrote "nevidím jídlo", but it wasn't accepte, because I've read somewhere that žrádlo means animals' food.