Did you report it to in-game support with provided screenshot?
Screenshot of what? Empty mailbox? Mail with rewards dissappear when you claim it, so what will it prove?
Did you do damage to the raid? Or attempt the raid at least twice?
Or the actual bug, where you attack the raid with a real team and say you did ~2mil, got a ranking, raids finished, and you didn't get rewards.
What a questions, man: of course i attempted it and did damage...
But guildmate found a solution: you need to restart the game to receive that mail. So if anybody get the same bug, just keep it in mind.