He's using menuahx.Test it out without a bootmanager. I had the same problems with DS Games but because it's a N3DS mh4u was not affected.
Just replace your SD:/arm9loaderhax.bin with the one from luma3ds v5.5 (make a copy first). If you do it like this, you won't need the pathchanger because thats the default path.
You don't need the luma3ds.dat either if you are on a9lh. Just replace that file from luma3ds.
Load up emunand with luma3ds then and test it again.
This step will make sure, that it's not the fault of your 3ds if it starts working.
That extended memory games not working because you're in emunand this is just bs.

