I kept my wallet.dat file in the safe storage, I haven't set the local wallet since I have multiple MN.. I wondered why i was hacked since I place all of my backup to my offline storage, no one use it this is my private external storage, and I also use a personal computer.. I think it is not the aws issue, because i have 2 left MN there, if they hacked my account they don't hesitate to get it all! I think it is the wallet, because it is not the first time I encountered it, the first encounter was on my wallet.dat I dunno it is very rare case but it was not working when i put it on my wallet storage.. How come the wallet dat will become corrupted.. I hope your team taking care of this issue.. that wallet I used in MN is never been used at any transaction except incoming when i sent coin to it from my main wallet. I never recover the BTC2 on that wallet.dat, I sent pm to jacklezz, i hope he'd remember it..
Your help is really appreciated since I'm one of your avid follower and voluntarily promote this project.. Again I had this issue, this is not good.. It is okay when the fault is mine.. But I took all the security measurement (except the local wallet.) to do the setup.
You can have multiple masternodes controlled by a single local node, with all the masternode collaterals in one wallet.dat, which you can optionally indeed put to encrypted cold storage after starting the masternodes if you don't want to monitor them. Your local masternode.conf accepts multiple masternode lines. So clearly you have set your masternodes up differently. Any wallet.dat copy you have is an access point to your coins, so all of them have to be secured.
Bitcoins also sometimes get stolen/hacked. Bitcoin 2 is not immune to it unless you keep everything secure. A masternode that is accessible from the web is an easier target than a local node and so if there's any coins on a web server's wallet.dat file, careful security practices are needed.
It is easy to make a mistake somewhere along setting things up if you are not careful or don't know exactly what you are doing. So far in 8 months no one else has reported such losses of BTC2.