[2021] Bug: If your deck has a Companion and more than 7 cards in the SB it shows as "Invalid" for Bo1 queues

Workaround: Clone the list and make a Bo1 version with only 7 cards in the SB.

Bug Description It seems any list that has 15-card sideboards including a companion is shown as "Invalid" for Bo1 queues, tested with "Play" and "Historic Ranked".

This list used to work fine for both Bo1 and Bo3, now it shows as invalid in Bo1:

Companion
1 Lurrus of the Dream-Den (IKO) 226

Deck
4 Clever Lumimancer (STX) 10
2 Clifftop Retreat (DAR) 239
4 Defiant Strike (STA) 3
4 Dreadhorde Arcanist (WAR) 125
4 Fight as One (IKO) 12
4 Guiding Voice (STX) 19
4 Inspiring Vantage (KLR) 283
4 Invigorated Rampage (KLR) 132
4 Leonin Lightscribe (STX) 20
4 Needleverge Pathway (ZNR) 263
3 Mountain (THB) 253
4 Reckless Rage (RIX) 110
4 Sacred Foundry (GRN) 254
4 Soul-Scar Mage (AKR) 175
4 Tenth District Legionnaire (WAR) 222
3 Plains (THB) 250

Sideboard
1 Academic Probation (STX) 7
1 Deafening Clarion (GRN) 165
1 Environmental Sciences (STX) 1
1 Expanded Anatomy (STX) 2
1 Inkling Summoning (STX) 195
1 Reduce to Memory (STX) 25
2 Infuriate (STA) 41
1 Lurrus of the Dream-Den (IKO) 226
3 Shock (STA) 44
1 Start from Scratch (STX) 114
2 Valorous Stance (JMP) 136

If you drop the SB down to 7 cards it shows as valid again. However, non-Companion decks like this work fine in Bo1 with a 15-card sideboard:

Deck
3 Wrath of God (AKR) 46
1 Commit /// Memory (AKR) 54
4 Lightning Helix (STA) 62
1 Dovin's Veto (WAR) 193
4 Memory Lapse (STA) 16
4 Expressive Iteration (STX) 186
2 Teferi, Hero of Dominaria (DAR) GR6
2 Teferi, Hero of Dominaria (DAR) 207
3 Narset, Parter of Veils (WAR) 61
1 Justice Strike (GRN) 182
4 Raugrin Triome (IKO) 251
4 Steam Vents (GRN) 257
1 Field of Ruin (THB) 242
4 Hallowed Fountain (RNA) 251
2 Sulfur Falls (DAR) 247
4 Glacial Fortress (XLN) 255
2 Clifftop Retreat (DAR) 239
1 Plains (THB) 250
4 Shark Typhoon (IKO) 67
2 Brazen Borrower (ELD) 39
1 Search for Azcanta (XLN) 74
2 Prismari Command (STX) 214
1 Mountain (THB) 253
1 Island (THB) 251
2 Sacred Foundry (GRN) 254

Sideboard
1 Dovin's Veto (WAR) 193
2 Baffling End (RIX) 1
2 Aether Gust (M20) 42
2 Rest in Peace (AKR) 33
1 Brazen Borrower (ELD) 39
3 Mystical Dispute (ELD) 58
1 Wrath of God (AKR) 46
1 Justice Strike (GRN) 182
2 Commence the Endgame (WAR) 45

Edit: Fixed second list, copy-paste mistake.