Monster Hunter 4 Ultimate on the Ayn Thor shows multiple related failures in Azahar when save/extdata/DLC files are moved into place. Depending on the exact file combination, the result can be:
DLC not being detected at all
extdata being treated as corrupted and rebuilt
fatal error / invalid ROM states in some swap scenarios
full blackscreen, especially once the game reaches a recognizable DLC state
This was tested across latest 2125.1-vanilla, 2125.1-Google Play, 2123.4.1-vanilla, 2121.2 and the 2125.1 nightly build. I also swapped files, folders, and APKs with user Luna during troubleshooting, who had absolutely no issue with dropping in MH4U DLC, so this was tested both solo and across another user’s setup.
Environment
Device: Ayn Thor
Game: Monster Hunter 4 Ultimate (USA)
Updates tested: 1.1 and 1.3
Azahar builds tested:
2125.1-vanilla, 2125.1-Google Play, 2123.4.1-vanilla, 2121.2 and the 2125.1 nightly build
What I tested:
Save/extdata injection tests
File management at this point was still using Filezilla on my Windows PC. I later realised this might be causing problems and will mark when I started using the Thor's own android file manager.
I tested all of the following on the Ayn Thor:
Fresh Azahar install, let MH4U create save/extdata, copied the same files out and then back in: blackscreen.
Same as above but save files only: blackscreen.
Fresh Azahar install plus clean 3DS-generated MH4U save/extdata copied in: blackscreen.
Same as above but 3DS save only: blackscreen.
Moving/touching files inside 00126300, including the system file, produced unstable behavior and often blackscreened past the circle pad pro popup.
Merely changing a file timestamp did not always blackscreen, so this does not look like a simple “any file touch breaks it” case.
I also tested without DLC as a control, and fresh dumped 3DS files could still cause issues.