I grew onions last year in a raised bed. It was the first time I planted onions in it. I had a few different types. I was late picking them but when I did I noticed the white onions were eaten all around the neck. They are not rotting but they seem cleanly eaten from the outside to just short of the center, top to about 1 centimeter down . When I noticed this I just left them there as I was going to pull them later. I now have lots of them sprouting and was wondering should I plant these as I don’t think I have a disease.
Sounds like slugs and snails feeding on the bulbs. Pull and dry off the bulbs as best you can. Sown as seeds in March or planted as sets in April, onions should be ready to harvest in September.