Yes 6 hours is absurd considering they use to remain for 5 days after you killed the invader or banished the ghost it is not so bad with the umber lairs as they are very fast to yield but the lv5 and lv6 lairs take a lot longer to empty even with hero present your talking 4 hours to empty, please return invader lairs and ghost shelters to the original remain time on the map as before, after a global event there use to be so many to yield but they vanish so fast now and the rss are just wasted that you could farm from them. 

I finally have to ask,why do you always call the uMbers , when the word is uber?

6 hours just does not get it for farming ghost or invaders plarium fix it or i quit 

Yes this is just way too short ... I recommend 12 hours for ubers and 24 hours for other invaders ...