Doing the Hawezar Helltide, collected ~350 Aberrant Cinders so I could open the Mystery Chests. I headed to the Mystery Chest in Southern Fethis Wetlands, and noticed a Cellar (Cursed Cabin) right next to the chest so I ran into it. I claimed the Shockwave Altar, killed a couple enemies + an elite, then opened the piddly little chest that spawned. When I left the Cellar, I noticed I had lost 100% of my Cinders. No death, and the Helltide still had 30 minutes left, so I have no Idea how this happened.
I went back to the same Cellar later in the Helltide (this time with only 32 Cinders), got a different event, and did not lose my Cinders this time. Not sure if it is the specific event or related to how many Cinders I had. Hope this helps!
World Tier 4, Conjuration Sorcerer, level 74, 8:45 AM PST