It is sometimes easy to miss item 37 on the diagram in the tech manual. This is a rubber seal in the piece that stays attached to the engine. It sometimes goes missing and is essential for proper oil circulation.
It does not come with the oil filter, and needs to be purchased separately.
Also be sure to check that you have removed the o-ring from the top of the filter housing. It is easy to remove with an angled-tip pick. If you don't pull it out and put another on top of it, you can crack the housing when tightening it down.