A number of people have been experiencing problems with large High Capacity Micro sd cards.

News went out saying it was a hardware problem, But this has been a misunderstanding , it is a firmware issue and will be resolved with the next firmware update! 

I would Like to apologize for the inconvenience this has caused to all of the M3 DS Real customers and resellers.

UPDATE :

The new firmware is now availabe in the downloads section. (V2.7d)  

What's new in V2.7b is available under read more. 

M3 V2.7b released:

1.
Fix the bug of the cheatcode format (".dht").

2.
NDS/GBA Linkage function is fully supported included "poke" series.

M3 V2.7a

--New Games 1712,1724,1685,1691,1699,1706:  software reset function are supported.

--New CheatCode switch option was added: 
1)Switch On(allow switch between on/off during game playing) 
2)Always On

--Improve the speed of listing games

--Support up to 128 games in 1 folder.
--Allow users to change the game folder. Just click the folder icon to change the default folder.
(4G/6G SDHC TF cards are well supported even more games are copied into.)