I was having an issue with playing iTunes extras. It was suggested that my AV may be the cause. I uninstalled Avast and installed another AV product and my extras started working. Is there a known solution to stop Avast from blocking these?
We can give you hundreds of (possible) solutions, but if you don’t have avast installed there is no way to tell which one for you will likely work.
I will reinstall it since I have paid for the full version but I was hoping to figure out if there was a known solution.
Likely something like setting up the firewall rules correct or add a exclusion can work.
Okay so I am very technical but not a network guy and definitely not a whiz with Avast Firewall configs. How would I setup a rule to exclude iTunes?
After you’ve installed Avast, you should be asked to allow the connection.
It must have pulled the config from when I had it installed before. It did not prompt me for anything and iTunes is setup for allow connections to all networks. I have attached a screenshot of the Packet rules listed for iTunes in case that helps at all.
You didn’t say if you’re still having a problem ???
It does appear that this is no longer an issue since reinstalling.
Sometimes, the quickest fix is a clean install. 
Clean Install of Avast:
https://goo.gl/4Ptzkf
If you need additional help with the Clean Install, watch this:
https://youtu.be/p-h3myRD51A