Yes, that's due to the nature of how we match flashcards against dictionary entries - the CHARS tab shows just an isolated character without a traditional/simplified variant and so it doesn't reliably match a flashcard that might have both character sets. (the reason why we do it this way is that otherwise you might have a flashcard for 幾 'how many' and not 几 'table' and nevertheless have both characters show up with [+] icons / be unable to easily create a new flashcard for 几 because it's a duplicate)
We actually never intended to show flashcard indicators in that tab at all, but we're worried that if we take them away in a minor update now we'll have people mad at us, so we're waiting for a better opportunity to fix or remove them.