This has been covered recently and I’ll try to find that, but essentially:
Single kanji vocab is a word, so wrong reading = wrong answer. If you put the wrong reading, you’re effectively spelling the word entirely wrong.
On the other hand, when you’re reviewing a kanji, the reading it’s looking for is the one that was taught (usually kun’yomi, but not always) so if you enter the other reading, it’ll tell you that you’re not wrong, but it’s not the answer it’s looking for.
Also…
\textcolor{pink}{\huge \textsf{WELCOME! ^-^}}
Even if you’ve been a member for a while, so aren’t really new hehe
Take the time to check out the FAQ and GUIDE if you haven’t already…
…but you probably have, because you seem like you’re diligent and awesome like that ^-^
There’s also a lot of good stuff on the forum to help you…
…that you’ve likewise probably already seen, but it still worth mentiioning!
The Ultimate Guide for WK
The Ultimate Additional Japanese Resources List!
The New And Improved List Of API and Third Party Apps
I hope that you continue to enjoy WaniKani that your worship of the Crabigator is eternal!