The same thing happened to me. Last night I swapped my g6lite into the gba cart so i could play while my ds was charging in the other room. I played Super Robot Taisen for an hour, saved and then turned off the GBA. This morning I put the g6lite back into the ds case and took my ds to the dentist. When I sat down in the waiting room and turned on the ds, I saw that my SRT save had reverted to how it was when I copied the save to the g6 earlier last night. It hadn't saved any of my changes.
I'm going to play around with it today and see if Real time save is messing things up.
I'm confused here.
First you said you put the G6 Lite into the GBA (big) cart, so you could play SRT on your Gameboy Advance. Then you said that later you reswapped the carts and took your G6L and DS Lite to the dentist (with you of course) and that the save had "reverted to how it was when you COPIED THE SAVE TO THE G6 LAST NIGHT".
You never mentioned copying any save to the G6 before.
When exactly DID you copy the save to the G6, and WHY and how did you copy it? It was already ON the G6 in the first place, wasn't it ?
Or did you have it on the computer in the Visual boy advance, and you had never played it before on the G6 ? .... or did you previously play on the G6L and had backed up all the saves to the computer, and then I'm assuming you deleted the game, then reinstalled it later, and later copied those saves back? You need to give this information ....
You also neglected to say if you were using real time saves or normal saves.
If you ARE using real time saves, here is the problem.
Unlike the ZSNES super NES emulator, when you *LOAD* a save state, it automatically rewrites the SRAM to match the sram that would have been present during that state save. Visualboy Advance does the same thing. I found this out the hard way, when I had reverted to before completing a dungeon in Final Fantasy 4 (when I had saved OUTSIDE, normal save, right AFTER completing the dungeon and getting Rosa cured), because I decided to load a save state, thinking that my save state was more current than my in-game save. It wasn't, and the in-game save reverted to the one that matched the place where I had last saved in-game, which became part of the save state.
So saving a game also saves the current sram state as well (most emulators ignore the sram, like ZSNES), while VBA writes the sram state as part of the save. Is that your problem ?