I challenged 2 person. After 24 hour now showing Expired but I got no XP. Why?!

Answer 1

working as intended

Answer 2

Well, the way Sololearn challenges work is you only gain XP if you either win or draw a challenge, with all other things either leading to you losing XP or not gaining anything at all. An expired challenge means that the other person had waited too long to complete the challenge, which doesn't give you any XP.