In the past week or so I am no longer able to tag my decks with a variant (Commander, Constructed, etc.) Is this a bug on the site? Does anyone else see this issue?

Seems to work just fine for me. Is it a premium feature?

must be the option is there, but greyed out.

Ah, it looks like it is. Unlike most of the premium features on the site that have a green checkbox, that particular dropdown doesn't have one. If you hover over the dropdown though there is a tooltip popup that mentions it is a premium feature.

I had enabled the free trial a week or two ago and not realized it was a premium feature, now that the trial has expired I have a mismash of decks with and without it set.

Thanks for pointing that out.

-Travis