My BAT balance is gone after verification

* Sorry for my poor English: I’m not a native speaker.

Briefly describe your issue:
After verifying my BitFlyer wallet on Brave, my previous BAT balance has vanished at all.
In addition, “Add funds” and “Withdraw funds” buttons on brave://rewards seem to be not working (just guided to the top page of BitFlyer).

What Operating System and Brave version are you using (Menu --> About Brave)?
Windows 10 Home
Version 1.24.85 Chromium: 90.0.4430.212 (Official Build) (64-bit)

Is your browser wallet currently verified? (yes/no)
Maybe yes. A message “Wallet Verified” is displayed in brave://rewards.

What date did you verify your wallet?
2021-05-17

Have you been able to successfully receive payments in the past?
This is the first time to transfer my BAT to BitFlyer account.

Are you using a VPN? (yes/no)
no

Are you in a supported region (see here for list of supported regions)?
Yes (Japan)