Issues with OS X 10.10.5, Pro Tools 11.3.1 & 3rd gen Mbox mini

[PJ Brady]

Hi Friends - If anyone can help me I would be extremely grateful. Basically, here is the problem. I have a Late 2009 Imac that was running OS X 10.8.5 Mountain Lion and running Pro Tools 11.3.1 via a 3rd Generation Mbox Mini with no problems. I have wanted to use Amazon Prime Video as well as Netflix that requires a more recent OS X So I updated it to Yosemite 10.10.5. I can not hear any sound from Pro Tools 11.3.1. I have researched online, looked at the Pro Tools compatibility chart and read old posts on hear from some years back. Originally, when OS X Yosemite first came out it caused various problems but I have seen that there has been updates since for Pro Tools 11.3 that solves such issues. But I am still not hearing any audio both from Pro Tools or Itunes with the 3rd Generation Mbox mini. I have downloaded the Mbox drivers from the Avid website such as 1.3 as well as 1.3.1 but still nothing. Any help and advice would be greatly appreciated. Thanks