“Go to Uphold.com and log in independently of the Brave Rewards verification flow. Once logged in, go into Brave Rewards and verify wallet. Follow steps Wallet verification should be successful (in 'Wallet verified’state)”
Follow this method. Taken from https://teddit.net/r/brave_browser/comments/o6apqk/uphold_wallet_verification_loop_android/
Also, make sure your shields is down, and third party cookies are available for some time.