Added an Echo Plus but SOME of the functions for Vizio Smartcast won't work

[djxpress]

Up until recently I had just an Echo Dot in my Living Room.  I just bought a Vizio PQ-65F1 TV which is SmartCast enabled and can be controlled via Alexa.  I also just added an Echo Plus to the mix.  I moved my Echo Dot to my bedroom and have the Echo Plus in my Living Room next to the TV.  Both are enabled and the SmartCast Alexa skill is enabled.  For some reason the Echo Plus will do all commands like turn on/off tv, change channels, change inputs, but it won't turn up/down or mute the volume.  If I give these commands to my Echo Dot, it performs them flawlessly, including to increase and decrease the volume.  I'm wondering why the Echo Plus will only do some of the SmartCast Alexa skill commands? 

I've reached out to Amazon Alexa's customer service and they've created a ticket.  I also reached out to Vizio Support via reddit and they're looking into it. 

I'm just wondering why my SmartCast enabled TV is capable of all commands working with my Echo Dot, but the Echo Plus won't do the volume controls?  They're all connected to the same network.  I've tried enabling each Echo separately.  I've reset the TV.  I've disabled and reenabled the SmartCast skill.  Nothing seems to work.