First thing to do, is to check the indicator circuit, is the switch operating correctly, is there any chaffed areas on the wire to the switch.
There is power to the switch, anytime the key is in the run position, and the switch just provides a path to ground through the switch, when there isn't enough oil pressure to open the switch.
There is a filter bypass valve at the back end of the oil filter cavity, push on it to see if it moves.
I had a similar problem back in 1983, just changed the oil, ran it, leak checked normal, no issues with the oil pressure light.
Next morning, started it to go to work, and the oil pressure light wouldn't go out.
Had the dealer pick up the bike, and they said that all they did was apply shop air pressure into the filter cavity area, I'm assuming that pressure was applied to the tube in the center of the filter, but I'm not sure, and the problem went away, hasn't been back since.
Their best guess was that the pressure regulator relief valve hung open.