I actually hate bringing up an old thread but it is almost 2 weeks since this came up… any solutions yet? What happens to the people that lost monsters on the 10x roll?
The support teams helped me get back what was lost mostly, they couldn’t see the last x10 style opening I did in the system I guess so I did lose out on a good legendary but they gave me some gems to open again to try and compensate! At the end of everything I do wish I could get back the one guy I cared about the most but don’t blame them if they couldn’t see in the system at all! I was just happy enough to get back what I did and that they responded to the problem 
I am still waiting for a reply from them…
Sorry have been busy lately.
Sadly, I can never get my 10 monsters back but devs give me 50 gems compensation which is also good.
So I can resummon.