hm yeah i get that sometimes
usually when i catch that sort of thing happening (also sometimes being able to read the word and having no clue what the composite kanji are, or as a separate problem guessing the meaning of a kanji based on a phonetic group which has a kanji with that meaning but having no clue which of these kanji is which), i intentionally fail the card and go look up the etymology and such which gives me a little more to grasp onto (usually if i can’t remember the word/kanji but can remember the card it’s because i didn’t spend enough time learning it in the first place)
usually its those kanji/vocabulary that i can only remember when WK gives them to me that i suddenly can’t read in context so i think it is an actual issue