Being out of parties doesn't save you from AoE Camellia. (I'm sorry, rogues!) ;-;
But yeah, this bug happens with several other buffs. Seems to be rather shoddy coding for rogues tbh since buffs shouldn't bring you out of Hide, unless it's something you casted yourself while in Hide.
Oh, I know about Camillia. When I'm playing Rogue (R/Wl) in Siege, if I'm anywhere close to a Druid casting that one, I'm probably already out of Hide and need the heals!
Call it a bug if you wish, but note also that if a Rogue in Hide happens to hit a regular heal pot, that brings them out of Hide, too. And *keeps* them out of Hide until the timed HoT ends or until it's cancelled. And any pot at all will bring them out of Hide. I guess the game considers it to be an "attack".