The device ID is used by the device to communicate with the web panel. "Renaming" the device starts the following flow:
1. The device is notified the it needs to be renamed
2. The device confirms that it changes the name
Unless this flow is completed, renaming is disabled. Otherwise, the device may be "lost".
Make sure your device is online; refresh the configuration on the device if possible. This should complete the flow and enable further renaming.
In general, renaming the device is an exceptional situation and shouldn't be used just for informational purposes. Use the "Description" field to store the temporary information about the device.