I have also the same problem.
I am calling the API with curl like this:
curl -H „Authorization: Bearer TGx4cUwyQjJUbzVMMHZBWjBmUkQ3WUtGenVsSjU1Zk9Gb25IMEY“ -H „Content-Type: application/json“ https://localhost/api/v1/product -k
Whereas the passed Bearer token I got from http://localhost/admin#/ and then Settings->System->Integrations (Secret access key)