I'm having very similar issue with one of our 04' ADVs.
I even put in NEW Oil pressure regulator and cam chain tensioners. Same thing.
I get the same noises even though the OIL pressure light is OFF as you showed.
Once warmed up and underway, it goes away and the bike runs great.
I have a Clear Clutch cover on the bike, so I can see there is Plenty of oil in the sump and it is pumping oil at least that far.
Looks like another winter project for me.
I'd like to get ALL the OIL into the Engine Sump on start up. It will pump it out and back into the tank when running, then I'll know I don't have an oil starvation issue. With the Clear Cover I can keep an eye on my oil lever, like a sight glass.
So, I pulled the check valve spring out of the Tank pick-up line, but left the Check Ball in place. Figuring I can test it and put it back together. (I was about 2,000 miles from home when I did this test) It worked the first time. All the oil drained into the engine. Perfect.
Then I started the engine and ran it until the sump looked normal. Killed it and the oil did not return to the sump? I'm thinking maybe some sort of hydro lock is happening with the ball and seal still in. I ran it the rest of the 7,000 miles trip.
Now that I'm home, I will pull the rest of it out of the check valve soon and retest.
If this is the case and quiets the engine, Why are we having an oil starvation issue on the INTAKE side of things???