sorry, looks like we missed this in our deployment / publishing guide: For custom splash screens just add a file named splash_1280_768.png (or splash_768_1280.png depending on your game’s orientation) for Z-based BB device models and/or a file named splash_720_720.png for Q-based BB models. We’ll add this information with the next release of our documentation!
Regarding sounds, have you noticed the “supported formats” notice in our documentation here? For BB background music you have to provide an .ogg file in case you’re trying a mp3 as of now.
Yes the name is correct, but I guess our Build Server was expecting a Q-model-based (720×720) splash image too. We fixed this in that minute so you now can provide Z-based splash images only like you probably tried before, sorry for the inconvenience!