@LauraJ this can happen for two reasons.
1. Classification being configured incorrectly. You may delete the classification created/modified just before the issue started.
2. Unable to connect to DB table.
You may check the Orion.log to understand the exact cause.
I've had a look in the Orion log, I cant see anything in this file that may indicate the issue unfortunately.
I'm unable to say when the issue started either, its only when we have come to apply another policy that we have noticed, at this point we have seen the error, I have removed what we added in but we still get the policy failed.
Yes, you can post it here OR create a service request with support for a technician to assist in remote.
I see you attempted to apply following policies and failed.
Seems to be the policy has corrupted. Try to restore the policy backup file and check.