hi, maybe it will help you. with shocks somethimes i got a air buble coming from the main oil tank to the 1l one in the engine. when this buble is in the small engine tank, it stops to pump oil from the main tank. our mechanician said this is normal, and there is nothing else to do. as suggested you can run your engin with the small tanl open and check if your oil pump is working and fill in the small tank. but you will have oil coming up the small tank, this is so,nething you have to do once to check your oil pump, after that i will suggest you to directly add oil in the engine tank. during my round of ireland we had this issue 3 times. not easy to fix in big waves.
if you have the same issue as me and found a solution please share it !