How come when I say show me all except commons - for example it does not show me my oblivion ring. Its an uncommon from M13. I have the M13 one and not the commons.

Oblvivion Ring was a Common in a previous set. I'm guessing it looks at all versions of the card to determine it's rarity so it'll be a Common/Uncommon.

How can I use a filter to make this show up when I search uncommon?

Bump.
...
Still trying to figure out how to see my uncommon / commons correctly...

Only Sebi will know if that is even possible. It is likely a limitation of the Application Programming Interface (API) or data dictionary from which this site pulls its information.