explorer bug?

Hey all, Can anyone tell me why this has happened?
I have 6 savage scouts and 2 normal explorers, I logged off last night b4 i got the daily reward, and I sent all explorers for a medium treasure search, this morning all explorers had come bk but there were only 4 treasures found! there should of been 8! This has never happened till now so can anyone clarify why? Whats the point of buying extra explorers from the shop if this can happen? Not happy!

Ok all scouts came bk from an adventure search ok and the normal explorers completed their medium treasure search ok. It mustve just glitched cause I had the daily reward quest chest appear as well but it somehow replaced 4 chests! weird. Ill have to send them out at different times to avoid this again.