@IT Support, Thanks for posting in Q&A.
To remove a policy that restricts copying files to USB, you need to check where we configure the policy. Here are some locations we can configure the policies:
https://www.prajwaldesai.com/restrict-copying-corporate-data-intune/
Note: Non-Microsoft link, just for the reference.
You can select one affected device, click "Device configuration" under it and check all the policies applied to it and find the affected policy. Then unassign the policy and see if copy to USB is working.
Hope the above information can help.
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