This is a bit unusual. It's not uncommon for a device to be initially detected as a host as there are several discovery methods that will really only identify the device's MAC and IP addresses. But generally it should be identified more correctly within a couple of minutes. However, it doesn't happen magically - there must be a discovery method used to identify what type of device it is. The options here include:
1. Discovery from Bonjour announcements. This will only work if the device is in the same VLAN as the probe.
2. Discovery through LLDP or CDP. The requires the device to be connected to a switch that is already managed by CBD
3. Discovery by querying the SNMP system MIB. This won't be an option here as SNMP is disabled by default on the switches and you mentioned the switch was at factory defaults.
You can check which discovery methods apply to this device by selecting it in the CDB inventory and clicking on the More... button to see the device details. The discovery methods are shown in the lower left of the screen. But from what you have described, I don't think any of these three methods is going to be the case here. Discovery is probably by either ARP table or MAC address table.
Manually adding the device probably won't change anything. If I had to guess, I'd say that when you were provisioning through PnP earlier, your configuration probably enabled SNMP, or maybe moved the management interface to a different VLAN that contained the probe. But now I'm just guessing.
At this point, it's going to be hard to say exactly what is happening without getting some more detailed information. I'm going to suggesting calling your local support number listed on https://cisco.com/go/sbsc and get an engineer to work through the problem with you live. In the end it will probably be something pretty simple, but they will need to understand the network topology and will probably ask you for some specific screenshots or diagnostics as they work through the troubleshooting process.
Cheers,
Dave.
