M3 DS Real won't recognize system

I've been using my M3 with an old 2gb micro sd, no problems at all. Today I bought a 16gb sdhc, pasted everything that was inside the 2gb micro sd into the new one and it won't boot.
I get to see the first loading screen, with the M3 logo, but I get stuck in a black screen after that. I tried formatting to fat32 and fat16, no luck. Only difference I can see between both micro sds are the size and the fact that the new, non-working one is sdhc.

Is this a known problem, am I doing something wrong? Any potential solutions?

 

I just noticed this in the back part of the box in which the card came:
"Supports the Micro SDHC specification, allowing for high capacity memory cards 4GB, 8GB..."

So I guess it is not about SDHC nor the size.

 

I tried already. I tried all possible options with that Panasonic program and with the one from sdcard.org. So it probably is not about formatting the card either...