Can you access Bluetooth services without Core Bluetooth?

We have some Bluetooth enabled tags here that can be scanned and connected to, but we are unable to access their services with CoreBluetooth's CBPeripheral.discoverServices()

We are able to access services on other devices using the same Swift code, and we are able to access the tags' services on Android devices, but something about the way CoreBluetooth and these tags interact does not register anything from these tags when requesting services. We're looking for ways that will allow us to bypass Core Bluetooth. Or, possibly ways of getting more finely tuned information from Core Bluetooth?