Unable to curl search requests returns 401 error

When I attempt a curl request with the following URL - https://my-gitlab-instance/api/v4/search?scope=commits&search=f1ae6d8b I receive error message 401 unauthorized.

I am not sure why this is happening as I am specifying a user account which does have rights for this. If i try the same username on a curl request to any where else it seems to work. For example I can curl just fine to /projects, /commits and many others. Trying to specify my private token also yields the same results not allowing me to access search but again projects works

Any ideas?

Thanks