Hy!
A week ago i buyed shadowlands epic on G2A and i got scammed(the seller refunded the game and right now he is refusing to pay back the money, but that’s another story). So I was forced to buy the game again. I cant unlock my boosted character. I get the “apply another boost to unlock the character” text, but when i do, i can’t select my character.
Hey Fortbenning, with Shadowlands only the Heroic and Epic Editions unlock a character boost on an account.
If your upgrade this time was with the Base Edition that won’t have unlocked the character boost for you.
If you did use either the Heroic or Epic Editions to upgrade again though, there can be a delay on the boost being ready for use. You may need to wait a few hours from the upgrade to use the boost to unlock your character.
As Chronormi’s linked there’s a guide for unlocking boosted characters, you can check out that as well 
Yes, i’m aware that i can’t unlock it with the base game (which is wierd because in legion and bfa you could do that but nvm.) thats why i buyed the epic again. I already made a ticket about it. I hoped someone else experienced this anomaly in the past. Thank all of you for your reply.
On the side note, as a software developer all i can say is, that you guys have some serious issues. There shouldn’t be a few hour delay… Look up what ACID stands for in database transactions. God…
In the past the boost was included with the base game, the SL expansion it’s only included with Heroic+ as advertised.
The delay on the boost is also intentional because most forms of payment fraud occurs within this moment. Think about stolen credit cards that are invalidated by the issuers, chargebacks etc.
i dont think this is a delay. I have the option to use it on my other characters.