iPhone 11 Pro on IOS 15.3 Has Wireless But Is Not Listed in Router Client List

My iPhone 11 Pro is updated to the latest IOS 15 (15.3). It is able to connect to both the 2.4 and 5 Ghz channels of my home network, and the wireless symbol on my screen confirms that connectivity. The Private Wi-Fi Address and Limit IP Address Tracking functions of 15.3 are enabled on my phone. However, when I access the Asus router's home page client list, my phone is missing from the list. As far as I know, the phone was listed before I upgraded to15.3. Anyone have any thoughts on why my phone essentially a phantom client on the router's client list even though it is on Wi-Fi? BTW, strangely enough, my iPad running iPad OS 15.3 with the same Private Wi-Fi and Limit IP Address Tracking as my phone is shown on my router's client list.