I'm trying to remember what event happened before Yixuan said this and what stake they had in stalling her
it was in 2.5's main story right after shungus recovers from losing her senses to the qingming sword (copypasting the dialogue from the wiki)
Everything is finally explained to Yixuan Shifu...
Though the part about Ye Shiyuan is still left unmentioned for the time being.
Yixuan: ...I see, no wonder you didn't want to tell me about Xiao'Guang's condition earlier.
Yixuan: Anyway, at least things seem to have turned out well in the end.
Yixuan: Xiao'Guang wouldn't have recovered without you, (Wise / Belle).
Lu Hengzhou: ...Just cleaning up the mess they made themselves.
Ye Shunguang: By the way... we couldn't contact you for quite a while, Shifu. Did something happen?
Yixuan: I was supposed to be here sooner. I tried to take a shortcut through a few Hollows, but I ran into trouble in one of them... so it took me a bit longer.
Lu Hengzhou: Not just "a bit longer." To be precise, you were trapped by an unknown enemy and were completely out of contact for a while.
Ju Fufu: Trapped?! Who the heck could possibly trap you?
Yixuan: They were extremely cautious in hiding their tracks, and I haven't found any clues yet.
Yixuan: However, judging from our brief encounter, they're definitely not weaker than me.
Yixuan: They were as strong as any
Void Hunter.
Pan Yinhu: A V—V—Void Hunter?! How could you possibly just run into an enemy that strong out on the road...
Lu Hengzhou: Clearly, someone's deliberately targeting Yunkui Summit.
Yixuan: I haven't quite figured that out yet, but we can talk about it later.
Yixuan: Speaking of Void Hunters, you mentioned earlier there's information about
Sunbringer inside the Hollow...
Yixuan: Hm... I'll need to discuss this with the
mayor.
i think it's possible it was remielle but the thing that throws me off is the "deliberately targeting yunkui summit" part, again i don't really know what reason she'd have to go out of her way to stall yixuan from returning to the temple