2015 YZ450 knock, engine noise

Have a 15 YZ450 that developed a pretty significant knock. It was perfectly fine, died, then started knocking after starting it back up. I have pulled the top end and everything looks great. No metal in the oil, head, cylinder, clutch everything looks good. I can't feel play in the crank. Has anyone seen this? I know I need to go ahead and split it, just wondering if anyone has seen anything similar.