If FBI says successful but the version does not change, your base game and the update have conflicting Title IDs (e.g., one is the World/Region-Free version and the other is region-locked).
: Obtain the v1.2 (1056) update CIA. Authoritative homebrew repositories like hShop list this as a "World" region file to ensure compatibility. Install via FBI : Open the FBI application on your 3DS. Navigate to the location of the update CIA on your SD card. Select the file and choose Install and delete CIA . pokemon ultra sun update 12 3ds world cia work
Pokémon Ultra Sun Update v1.2 CIA: Ultimate 3DS Setup & Troubleshooting Guide If FBI says successful but the version does