Kanye West Not Upset at Jay-Z Diss on 4:44 Album

Kanye West isn't sweating Jay-Z's diss ... unless he just hasn't heard it.

Yeezus was at his studio in Calabasas Friday looking happy, healthy, and oblivious to Jay's new lyrics ...

“I know people backstab you, I feel bad too / But this f*** everybody attitude ain’t natural / But you ain’t the same, this ain’t KumbaYe / But you got hurt because you did cool by ‘Ye / You gave him 20 million without thinkin’ / He gave you 20 minutes on stage, f*** was he thinkin’? / ‘F*** wrong with everybody?’ is what you sayin’ / But if everybody’s crazy, you’re the one that’s insane" on Jay-Z's new "4:44" album.

We broke the story ... Kanye's goal is to get back on tour as soon as early 2018, so maybe he's just got bigger fish to fry. And, he's writing new music.