Upgrade Finder - Mythic + Items?

Not sure if I am doing something wrong, but I would like to find upgrades available in mythic + levels, like a mythic 10 piece which would be an upgrade. Are mythic + items not supported?

In the filter options (Funnel Icon just left of Top button) you can select the Mythic+ level under Item variations.
Then in the Upgrade, select Dungeons.