I'm a new user struggling with some basics. I'm scanning a site as a POC for a larger implementation and only one of the assets, the VM I'm running the scan with is reporting the OS. I do get a selection of other data, so it's not a total loss but OS is key for our needs at the moment. Most of our hosts are Ubuntu, Centos or Red Hat and none of them are reporting the OS. I've been using one VM as a guinea pig and have an admin user with root privilege (root passwd may not be practical) and SNMP with a known public string that works.
If there's a page that describes how to troubleshoot this issue I'd be grateful for the pointer. Alternatively if I've omitted something blatantly feel free to help me up.