Was this underwatering? Or maybe it got stuck somehow when developing so got deformed? The rest of the leaf appears to be ok as well as the bulb and new growth elsewhere, tho the other leaf is missing. I’m trying to read up on this type of orchid tho I don’t know what kind of coelogyne it is. Biggest takeaway I’ve gotten so far for these types is don’t let them dry out which is great because u already saved me from my first mistake since I think I’ve always been underwatering my phals. Ty all for the help u give on this forum!