Shadow Flare disappearing in Shisui second boss

[Waliel]

Date & Time: 2018/08/17 7:20 ST
Frequency: Possibly always, tested once
World name: Cerberus
Character name: Waliel Hla
Monster name: Shisui dungeon second boss
Class/Level: SCH 63
Party or solo: Party

When walking into any of the chests in Shisui second boss, your Shadow Flare will disappear immediately. Might also apply to Sacred Soil, but I wasn't able to test that. I walked into the chests fairly quickly after putting Shadow Flare down, if that has anything to do with it.

Edit: Ran Shisui again and Sacred Soil also disappears. First thought was the "Old" debuff sharing the same aura slot (or equivalent) as Sacred Soil and Shadow Flare, thus overwriting them when you get it from the chest.