Eternal Flame Event Super Rare?

I've done somewhere around 25-28 chaos runs now for the new season, and I've gotten the eternal flame event twice. Both were at very low difficulties, 3 star and 4 star equipment only. About 12 or so 5 star equipment tier runs, not a single time event has proced, even though multiple runs I had the increased rare unidentified area fate. Is it just me being super unlucky or does this rare unidentified area seem to be super rare? I remember getting Chimeranite ore maybe 1/3 or 1/4 runs last season. Are there specific hidden conditions one has to fulfill to trigger this event?