Maybe there was something in the check valve, seems to be okay. I need to run it around now, have the feeling it’ll come back with surging on the overrun that I still need to solve !
youtube.com/shorts/mgY3FW4JbsM?feature=share

I agree with MarkT it’s fine just like a clear fuel line does  its pumping oil in the engine maybe DEET will chime in 

Yes, that line is open to crankcase pressure pulses so you will see bubble bounce. Only way to test if pump is working is remove line and measure output per manual. 

From experience I know for a fact that if pump sucks air or supply tank runs out of oil, line will show bubbles and then will go dry.  If pump quits, line can stay completely full.  Happened to a friend of mine...  he forgot to reinstall pump gear but didn't think there was a problem because he saw oil in line.  (Tach not working should have been a clue) And again, oil can be flowing fine with that air bubble just like the fuel does. 

Clear line is pretty much useless unless you want to use it to see when you run tank low or out of oil. In my experience you guys are just chasing your tail.  Which is okay as long as you're having fun.  

In the video at the start of the post the line appears to rise above then fall to the cylinder fitting. Is gravity tipping a few drops in when motor is stopped.
Black line cures all. Same with fuel lines. What ya can't see you won't worry about. Except, umm, you've seen it now.

You’re right, the oil pipe does rise up above the fitting, maybe when it’s really hot, the oil is just trickling in like a fuel line does and then never actually completely refills the line. I will try shortening the pipe and spinning the banjo fitting, see if that’s better. 
Just wondering if anyone has any thoughts on the relocated feed on later bikes ?

Update today, rotated the banjo downwards by a few degrees, problem gone !! 
youtube.com/shorts/13kWgoKkvB0?feature=share