Monster Hunter XX was released on March 18th, and pretty quickly, players encountered issues with the SD Card (which could not be recognised by the game). Capcom did release an update a couple of weeks later, and changed the way save data was handled in order to minimize the chances of the issue popping up.
But unfortunately, it’s only this week that the developers found what was causing that issue… and it turns out it wasn’t the game, but the SD Card itself (which is why it took them so long to find the cause)!
In a notice posted on the official website, Capcom explains that the issue arises when using a faulty SD Card. Basically, corrupted data is generated, which then triggers the issue causing the SD Card from not being recognised by the console.
Unfortunately, the solution is quite radical: delete the corrupted data and use a different SD Card. If you keep using the same SD Card even after deleting the corrupted data, the issue will inevitably arise again. In fact, you may even start getting issues with other games, which is definitely something you want to avoid.
Capcom notes that the update released a few days ago did help with the issue (without really fixing it), and that if you’ve never encountered it, you can keep palying without changing the SD Card as you should not encounter it in the future.