(PC, Epic Games Store)
I was trying to play Alchemy, (tried Ranked and Unranked) with a newly made deck and it consistently returns with a "Invalid Deck: Deck validation failed." message after I select "Play".
No further information as to why the error is occurring is displayed, preventing me from resolving the issue on my own.

I have tried removing cards one by one and playing, then adding them back when the error still occurred to narrow down the cause of the issue, but was unable to play, leading me to believe it's not an issue of a single card type in my deck.

There are no warnings displayed in the Decks screen, or when I attempt to edit the deck.
Exporting/importing the deck into a new one has not worked, neither has cloning the deck.
I only have styles for "Karum, Violent Cacophony", and it doesn't work with or without that style applied.

Deck
11 Island (ANA) 3
10 Mountain (ANA) 7
1 Sulfur Falls (DAR) 247
2 Spirebluff Canal (OTJ) 270
1 Niv-Mizzet, Visionary (FDN) 123
1 Ojer Pakpatiq, Deepest Epoch (LCI) 67
1 Melek, Reforged Researcher (MKM) 430
1 Charged Conjuration (Y25) 14
1 Ral, Crackling Wit (BLB) 230
1 The Apprentice's Folly (WOE) 200
1 Lilah, Undefeated Slickshot (OTJ) 217
1 Kylox's Voltstrider (MKM) 215
1 Shantotto, Tactician Magician (FIN) 241
1 Stormcatch Mentor (BLB) 234
4 Teach by Example (FDN) 666
4 Illuminating Lash (Y25) 23
4 Accident-Prone Apprentice (Y24) 16
3 Malcolm, the Eyes (OTJ) 219
4 Shellfish Scholar (Y25) 7
2 Kraum, Violent Cacophony (OTJ) 214
2 Johann, Apprentice Sorcerer (WOE) 207
2 Housemeld (Y25) 5
2 Alania, Divergent Storm (BLB) 204
1 Thousand-Year Storm (GRN) 207
1 Ovika, Enigma Goliath (FDN) 663
1 Brass's Tunnel-Grinder (LCI) 135