Home Sharing is not working following update to iOS 5.1 and iTunes 10.6

First, the problem:

I am not able to see any shared libraries when using the Music and Video apps on my iPhone 4.

Next, the specs:

• iTunes 10.6 on MBP running Mac OS X 10.7.3
• iPhone 4 runinng iOS 5.1
• Wi-Fi connections for both MBP and iPhone 4
  • Both connect to same network using same SSID with static IP addressing and UPnP enabled.
  • MBP connects using 5 GHz N-Only anntena.
  • iPhone 4 connects using 2.4 GHz NG-Mixed antenna. (Hopefully next iteration of iPhone supports 5 GHz.)

Third, what I have tried:

• Everything in "Troubleshooting Home Sharing" (KB Article TS2972 - http://support.apple.com/kb/TS2972).
• Re-entering my Apple ID credentials for both Music and Movies in iOS Settings.
• Re-entering my Apple ID credentials for Home Sharing in iTunes.
• Setting up Port Forwarding for both the iPhone 4 and MBP in my router for the relevant TCP and UDP ports (just in case). However, this did not help.

Finally, what I have noticed:

• My Remote app on the iPhone 4 works without issue and can control iTunes running on my MBP.
• My Air Mouse app on the iPhone 4 works without issue and can control my MBP.
• My wireless printer connected to the network via the 2.4 GHz antenna (it only supports 802.11g) is usable - I can print to it and access its embedded web server management tool.

So, in the end, Home Sharing no longer works on my iPhone 4 after updating both IOS and iTunes (all other apps and software updates are current for both the phone and the MBP). I believe I have ruled out any issues with which antenna is being used for which device. I am out of ideas on how to get Home Sharing to work again.

Any suggestions or possible solutions would be greatly appreciated! Thank you gurus in advance!