In a Brave Browser New Window, go to: brave://rewards-internals/ and take a screenshot (or 2, in order to cover all the real estate) . . . and report back here.
The two fellows’ Brave Community search results, mentioned above . . . those fellows know the mechanics. My guess, is that, they will know exactly how you would proceed. The screenshot(s) may help them, zero in on, how to help you.
In the meantime . . .
Simple steps (and my guesses):
Restart Brave Browser completely (probably DONE)
Update Brave Browser to latest version (DONE)
Disable all extensions, temporarily (NOT YET DONE)
A bit more work:
Try a new Brave Browser user Profile for test purposes (do not import anything; do not add any extensions)
IF by using that new Profile, Rewards works, THEN the Profile with the issue, has an issue.