Bumping this thread. Almost a month since the original post and this issue persists.

Fix the **** game.

3 weeks later and the direct challenge feature still isn't fixed apparently.

Yes same! I also have a Mac and wondering if it's an only Mac issue

I have also been experiencing this error still

Seemed that commander was not in place when deck selected for edit, because it showed exclamation point as not legal, even though it is legal and complete in deckbuilder view.

this problem still occurs for me on PC, is it ever gonna be fixed?

Having the exact same issue.
All Brawl Decks are considered invalid because of non-Standard Cards.
But even selecting a Standard Deck gives an error response of "there's no Commander in this Deck, so you can't play it".

It should work if you use the Direct Challenge Icon (the crossed swords near the top) and not from your friends list. If you each direct challenge each other, click the little drop down arrow under "challenge", and select brawl, you can Historic Brawl your friends.

This is completely unacceptable. This is HOW I play this game.

I have still been having this issue on my MacBook as well. Brawl direct challenge worked just fine on our iphones, but have yet to get it to work on anything else. Hopefully it gets resolved soon.

Same issue

additionally, when selecting the edit deck from direct challenge it has changed the deck t o 60card standard. Also afterwards if you go and then select the same deck from the normal deck editor it changes the 100card historic to friendly brawl.

I was able to play on the iPad iOS but my partner send me a screen shot of warning symbol on the load screen.

this has been going on for a week.

kind of sucks because I help my local games store for FNM and we use midweek magic and the direct challenge to help continue FNM, we have "commander nights" and we haven't had a chance to run brawl well at all.

Additional screenshot of this issue.

I also cannot play against my buddy through direct challenge brawls. For additional info:
He current plays on mobile, I play on PC. Does not work.
He plays on mobile, I play on mobile... direct challenge does work.

So it's not an account problem, it's a client/launcher problem. Whatever they did to break this, I wish they would hurry to fix it.

same issue on my PC as well

It's more than that -- basically, in Direct Challenge you can only select Standard decks. This is true even if the game type you've chosen doesn't allow Standard decks, like Brawl. But it also means you can't play Historic 60-card decks either.

Yep, I also can only select standard decks, which obviously error when you try to use.

I get this on PC too… interesting because it works as expected on iOS.

I would like to see historic brawl also an option for challenge games.

Same issue here, can only select standard decks in Brawl Direct Challenge which comes up with "invalid deck type" when initiating the game, and my definitely valid brawl decks are marked as invalid on the selection screen.

I can, however, successfully select those same "invalid" (not actually invalid) brawl decks for matchmaking Brawl, which means it is only not working in Direct challenge specifically for me. This is not the case for my friend however and he can select decks like normal in any mode, so it's clearly not an everyone bug.

I'm having the same issue on Mac as well High Sierra 10.13.6