So many of you have been having an issue syncing to your Uphold accounts on mobile. I just figured out the problem. I just verified my Uphold account using Brave Rewards feature on Android mobile app!
You have to drop your shields temporarily to complete the verification, because Uphold is technically a third-party source and the Brave Shield blocks the authorization cookie so Uphold cannot confirm your authentication once you submit the request
So before you sign in, tap the Brave logo and toggle Shields to off, then tap the Brave Rewards icon and attempt Uphold connection again! Finally it will work!
Toggle Shields Off
Open Rewards, Sign into Uphold, Confirm Username/Password of Uphold Account
Rewards Get Added