Thank you for reporting this and for sharing your experience with us.
We are aware of cases where Gauntlet rewards may not be received once the event ends. After review, we can confirm that this is related to the current event rules: in order to be eligible for Gauntlet rewards, players must complete at least one challenge after qualifying for the event.
If no challenge is completed after qualification, rewards will not be granted.
We understand this may not be clearly visible in the current flow, and feedback like yours is very helpful for improving how this is communicated in-game going forward.
Thank you for your understanding!