Hi Victor! Thanks for the reply. I'm running Version 11.5 (11E608c). As mentioned in the original post, even the default SpriteKit project is pitching the error, when it should be a working demo right out of the box. I've also got another project that I'd been working on extensively that has never required me to set the Module field before, which is now on hold while this is being sorted out. Not sure if it is related, but a bug just started showing up on this mac where audio/video files refuse to play in any apps, and any videos in Safari get blitzed in a half-second.