I checked and it seems that Wanikani doesn’t have any vocab using ぎょく, so it really doesn’t have any need to teach you the on’yomi (you can still learn it though)
たま is the Kun’yomi by the way.
What Log said.
Most kanji are taught as on’yomi but some are taught as kun’yomi. It can be confusing at times but the WK team picked the most common readings to teach for the kanji instead of always using one or the other.
I think the logic is that it’s easier to learn extra readings or meanings for kanji and append them to your existing knowledge, rather than learning a huge dump of readings and meanings for kanji right off the bat, so wanikani will keep it to the most common readings and meanings initially and you will learn more as you go when you study or read externally. 掛かる has many more meanings than “to be hung”、 and even kanji like 下 here where you are taught the か、げ、した、くだ、and さ readings have more than that.
Kanji can be a nightmare, best not to worry about every possibility off the bat or you will drown. Just learn what you learn as you go, and if you learn stuff outside of wanikani to add to your knowledge, great! That’s what it’s all about.
Ohh wow! I didn’t expect so many replies that quickly.
Thank you for your help everyone. What struck me as odd was the fact that I thought that WK always teaches you the On’yomi of the Kanji is Kanji lessons. “It couldnt’ have been ぎょく if たま is the on’yomi reading” was what I thought.