Hub service can't access private issues

Hello,

we are currently using an external Hub instance and have 2 services attached to it. A YouTrack service and a custom service for our 3rd party app integration (I'll call it Tracker from now on). Using the oAuth API we retrieve a client_creditentials token for YouTrack scope access so Tracker can read issues from YouTrack. We get the authorization token and it works perfectly for public issues, but we have a problem accessing private issues (available to the internal company group).

How can we allow our service to access those issues. Currently if we try to retrieve a private issue using the API, this is what we get as a response:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<error>You have no access to read issue.</error>

Best regards,
Igor.