Microsoft 365 copilot not working in Word

Hi
I Bought M365 Business standard and M365 Copilot for me ( India) and it is working perfectly.
I also supported one of my customers to get the same thing in the US. The issue is the following.

1.Working Perfect in Excel qnd Outlook.
2.When we open Word or Powerpoint it just does nothing and the Browser page becomes Blank.

Please suggest how to get out of this issue