I'm having the exact same issue with CentOS and Rocky 8. It looks like the agents are unable to download the trusted application and exception lists from the fleet server. As I understand it, these lists were previously served by Kibana and the functionality moved to be being served by the fleet server. It looks like the fleet server is downloading these lists successfully from Kibana but it is not making it to the agents.
I also had the same problem, what I did was delete the index which has the malware artifacts and re added the integration to the policy.
You can try the below command to delete the artifacts DELETE .kibana/_doc/endpoint:user-artifact-manifest:endpoint-manifest-v1
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