Interesting. Yeah it definitely came out the cup. After that I was initially able to feed liquid from the calliper to the lever. At the start there were loads of micro bubbles, frothy almost. Then it got better.
I bled (or tried to) as per the shimano R8070 dealers manual. Fill from the bottom, gravity bleed to remove bubbles, depress lever and open/close valve on the calliper quickly. Oil in cup and pump lever, moving bike angle and tapping everything to get bubbles out.
That wasn’t doing much so I started again and no oil would pass through the system.
I have tried loads since and it looks like I can’t even gravity fill/bleed with a cup at the top. I even left it overnight with a full cup and the hose disconnected at the calliper. Nothing left the cup. But if you pull the lever, oil comes out the hose at the bottom.