Hmm, I don't think it's 32 GB that's the problem so much as the card being class 10 (but since at least some Sandisk class 10 appear to be fine, maybe it's the quality of the class 10 card in question). I used class 4 Sandisk 32 GB cards to be safe, seeing as Nintendo has a tendency to drag their heels on this type of thing (i.e. not supporting SDXC -- at least, it's not mentioned in the manual). I get the GW3D text on both USA and AUS models. For what it's worth, I'm using the Sky3DS to launch both (by the time I noticed the new version was out, the Sky saves had already come out, oh well, this is good, didn't want to lose my save anyway). Getting the big size (1,979,711,488) for both of my NAND dumps. Well, if worst comes to worst, just make two N3DS versions of the app. One for 1.2 GB EmuNANDs, and one for 1.8 GB EmuNANDs.
If you're concerned, the best trick I know of is to enable parental controls in SysNAND. Then you know for sure you're not getting kicked back to SysNAND for some reason. Just go into the Internet Settings and see if it asks for the pin, if not, EmuNAND must still be running.
1 Is there another tool to extract and inject emunands?
2 Is there a way to uninstall the gateway exploit? everytime i click on profile/.... it kicks me into the gateway menu
1. None that I'm aware of, otherwise I wouldn't be eagerly watching this thread for an N3DS update.
2. Play a DS game / play a DS ROM on your DS flash cart of choice (mine's the DSTwo). Then go back and modify your DS Profile as needed. Re-Run the GW_Installer.NDS ROM from the blue card (or any other DS flash card) to re-install the exploit after making any needed changes to your DS profile.
If you're certain you're connecting the correct memory card to your PC (the same one you put Launcher.dat on), try another card reader. I've never had any problems with it myself.
I actually suspect they knew about this bug before release, and haven't yet worked out how to fix it.
Remember when the N3DS Gateway unveiling video was released, everyone assumed that there was no EmuNAND because there was no GW before the firmware string.
My guess is that this bug has been around since then.
Considering the video was posted when 9.2 was the latest, I've always been of the impression EmuNAND either wasn't running because the latest firmware was exploitable, or that they just didn't bother putting the "GW3D" notification on a private test copy. No reason to do the extra work putting safeguards on something you're not releasing. Also, it seems to not occur on the original cards that come with the system, either. I've not even been able to reproduce the bug on two systems using 32 GB cards, both being class 4. It seems to only be a problem with certain class 10 cards. It's doubtful they'd use class 10 on a test system (usually you want to avoid changing anything that doesn't need to be, to reduce the possibility of external factors causing your experiments to fail).