Date & Time: 16/03/2018
Frequency: Only happened one time
World name: Jenova
Character name: Arlie Lurkromdur
Class/Level: WAR/Elemental Lv10
Party or solo: both
Area and coordinates: Eureka

Steps:
1. Went to level with my group in Eureka.
2. Left normally for about 3 hours.
3. Returned to Eureka solo
4. Discovered I had dropped from elemental level 10 (almost 11) to level 8.