Calling GetOrders on the fulfillment API using the OAuth access token works correctly but only once.
Subsequent calls using the same access token even though it is well within it's expiry window always fail with "Invalid Access Token". If I fetch a brand new access token it works again.
Are these access tokens single use and I should be destroying them after each call to the api?
The documentation here: https://developer.ebay.com/api-docs/static/oauth-client-credentials-grant.html suggests I should be reusing them until such time as they expire