That looks excellent.
I took the oil filter off and oil soon started coming out. Put it back on and within a few seconds oil came out at the top end and then all over my bench and the floor as I hadn’t noticed it was working. Not sure whether taking oil filter out and back in helped or just coincidence but it’s working now so all good.
Good news then
it's always a little concerning and nervous time if you don't see it coming up as expected.
The bleed through, I suppose it's logical in that the system when closed with filter housing in place will run at 60psi with oil in it. So resistance to pumping the oil supply against air pressure may be just sufficient enough to prevent the oil filling the pump head (classic air lock) with the pump unable to draw oil through by trying to pump air, if that makes sense.
In reality, with the filter off and if the oil was warmer it would in all probability nearly run through there under gravity.
Nevertheless, it's the earliest point you can check for oil pump output to see if it's really pumping anything, and easy to do to. As you found, once the pump is going the rest will fill quite quickly.
