I have a friend who is also trying to get it to knock it off their completion list without luck. RNG simply sucks sometimes, especially when there are multiple seed types available on the same set of nodes.

I'll give you the same advice I gave him - wait until you have Luck of the Pioneer. It's not worth stressing over at low levels when at a higher level you can force seeds to appear. That should allow you to get any seed without trouble.

If you continue to get only the Onion Set after repeated use of Luck of the Pioneer, then it would be worth submitting a bug report.

Also, you can add edits to your original post rather than replying to yourself repeatedly.