Node shows in knife, but not Automate

I have a Chef Server with 427 nodes. 419 of them show up under the infrastructure tab in Chef Automate. What is the best place to troubleshoot why the other 8 are not appearing?

The Chef Clients are sending their data through Chef Server to Chef Automate, so I'm guessing something is getting dropped between Server and Automate. But these are individual nodes, not individual client runs. It isn't just one run that gets missed.

Any ideas?

@kmacgugan was able to figure it out. The chef_guid was the same between several nodes, so Automate was overwriting the data and was only displaying the data from one of the nodes at a time.

In my case, the C:\chef\chef_guid file had been copied as part of the machine image that was being provisioned. So I'll just delete the nodes and clients, remove the C:\chef directory, and put the validation.pem back in place and start chef-client over.

Thanks to @kmacgugan and @sdelano for helping me.