its been like that for year never been fix its juste sad that they never give a dam about that i think its there server cuz it depends of the time of the day the worst part is it keep changing the format of my deck and i need to put it back all the time its a shame that my favorite game is that bad

Check your sideboard as well. I had some invalid cards there.

this goes with my other comment

I have built a historic brawl deck and it is saying the deck is invalid, but non of the cards are highlighted, or any indication of miss used cards are banned cards. all of my other decks i have built from scratch work but nit my svella deck.

Same problem.

I’m having the same issue, specifically with Zendikar Rising.

I added every single card one at a time, saving and exiting between cards...

You can add 2 hullbreakers.. but when I add the third, it says my deck is invalid..

Built a dragon deck and am having the same issue, cant build the deck because "wildcards needed to complete: x" but i have every card in the deck.

I cannot build any deck at all, I have the cards for the decks, but every time it says "Wildcards needed to complete: x" - but I still have those cards and couldn't craft them with Wildcards if I wanted to, because I still own them.
So what's the point in playing, if you cannot build decks anymore? I don't get it, why I'm not allowed to do this anymore :-(

having the same issue. i also don't have any 0 quantity cards.

mine isn't allowing me to use cards I own even though I own them

This issue can be resolved by recreating the deck: do NOT copy.

What's happening is that when you remove certain alchemy cards from the decklist, the decklist maintains a 0 count for that card; even though the card isn't showing in the decklist. This keeps the invalid card in the decklist, making the entire deck invalid.

To verify if this is the issue for your deck, export the deck out of game to a notepad or other data holder. Look at the decklist for any 0 quantity cards. If there is even 1 in the decklist, the decklist will be invalid until you recreate the deck and delete the invalid one.

Same with multiple decks, it shows cards as invalid but I remove and re-add and it's fine. You can see in the attached pic I have 2 wizard classes selected but for some reason it keeps changing them to a version of the card I don't have. Also does the same with Phylath,

I'm having the same issue, but my deck warning started a number of invalid cards despite none being flagged in the editor. I removed the two legitimately invalid cards from one deck and count went from 2 to 3.

Same issue here

I am having the same issue how did you fix it ?

I'm having a similar issue - trying to select a standard deck that is flagged invalid, but no invalid cards for standard format showing in the deck builder.