DraStic

Sometimes the autosave on suspend/pause doesn't work, which may cause the player to lose progress even if the player isn't relying on it.
Here's what happened to me today:
I have Castlevania: Order of Ecclesia as a shortcut in my launcher. I opened the game using the shortcut (it resumed my previous suspend savestate), played hours through the game. I made several in-game saves in this play section. I stopped playing for a couple of minutes, and when I attempted to play again I pressed the game shortcut it loaded the same savestate loaded in the beginning of the earlier play section. That wouldn't be much of a problem, but loading that savestate replaced my in-game save with the previous one so I lost several hours of gameplay.
This has happened before with other devices and older versions of Drastic.
I'm currently on the latest beta (build 71), using a Galaxy S5 (Android 5.0).

That is why that annoying little popup appears if you load a savestate for the first time warning you about using savestates. Before I close down drastic I always make a quick save and I have auto save turned off due to it burning me in the past pretty similarly to what happened to you, but with different emulators on different systems.

Emulator best practice to avoid crashes/other bad things eating all your progress is to make multiple savestates on different slots and to make some hard copy in game saves too sonyou have no onw point of failure and can come back with at least most of your progress if something happens.

Example Final Fantasy TA2
I make an ingame save on slot 1 before I go into a battle with a savestate save too on slot 1
Durring the battle every 10 or so turns I make a new savestate save on slots 2-X with no in game save since it suspends the game and sends me to the main menu.
After I win (or I guess lose, hasn't happened yet but well you never know) I make an in gsme save on slot 2 and a savestate.

Another solution would be to disable "Store in-game Saves in Savestates" under Advanced Settings, although apparently that causes issues with certain games if your in-game save is newer than your savestate.