Using:
PkHeX 221218
Switch FW 15.0.1 / Atmosphere 1.4.0
Violet - 1.1.0
Currently at 1st pokemon center
JKSV 09.01.2021
Dumping the save and restoring the same save works fine.
I've edited the save to have a few new ditto in the box, and the pokedex to have all pokemon as seen, i also handed them a few ability patches as held items. When writing that save back via "Restore" in JKSV, I get hit with the "save couldn't be recognized" error.
The legality checker seemed okay with the pokemon, and I was able to restore the non-modified save without issue, so I'm not sure if there's something else I'm doing wrong. The file sizes are the same.
Anyone else having issues? Do I just need to progress further?