Microsoft Graph -- InvalidAuthenticationToken

This particular issue is only affecting MacOS -- when calling https://graph.microsoft.com/v1.0/me/calendar/calendarView, via proxy, and only via proxy, an InvalidAuthenticationToken response is received:

{
"error": {
  "code": "InvalidAuthenticationToken",
  "message": "Access token has expired or is not yet valid.",
    "innerError": {
    "date": "2021-02-03T19:48:11",
    "request-id": "445f0412-0d65-4c32-aa3f-bb0e922aade0",
    "client-request-id": "445f0412-0d65-4c32-aa3f-bb0e922aade0"
    }
  }
}

If the same request is made outside of a proxy, no error is returned.

Has anyone encountered this issue before?