Hello there! I am Charity, I'm an Independent Advisor. I'm glad to help you today!
Please try accessing the rewards via browser.
https://rewards.microsoft.com/
If the Rewards dashboard appears, the issue may be specific to the app rather than your account.
If you're still having issues, please contact Microsoft Rewards Support for further assistance on the link below.
https://rewards.bing.com/support
Kind Regards,
Charity
Please note that things might need more than one reply to completely resolve your issue, as it will completely depend on the complexity of the question and the amount of detail that you have provided me.