Why does this happen? It's happened to Project Mirai DX 3 times now. Once to MH4U. Why is this a thing?

But I use a GW.
Well I usually back up my sav files once in a while but I had not played this game in a bit so I didn't back up in a while. MHX saves to the SD card directly so I had not backed up. It annoys me that it corrupts the save file when this happens too. But when I looked up NTR it was a CFW thing and I don't see how that would help me when GW has to be in GW mode.I thought gw and ntr worked together? I assumed you could use the rts to help save more.
I wish someone would make a GW home brew app that did cloud backup of your .Sav files
