Strange 3.10.3 Optical Input Problem

The optical input on my Powernode 2 is connected to a TV. 

After the 3.10.3 update, contents streamed directly by the TV (e.g. Youtube) still work fine.  However, when using the TV as a PC monitor and sound device (connected via HDMI), the sound would be frequently muted momentarily, 1 to 10 minutes apart.  This was never the case before the 3.10.3 update.