I am trying to play a Spotify playlist through Amazon Tap (Alexa) using the iPhone app.  If I connect directly to the Tap through "Spotify Connect", many of my local files will not play through the Tap.  If I try to pick a certain song directly through the app, I get a message that states "Sorry! You can't play this content while connected to another device" (Screenshot is below).  I have synced this playlist numerous times, and all of the songs have a green arrow next to them.  There also doesn't seem to be a pattern as to which local files work and which will not work, so it's hard for me to diagnose the issue.  

Furthermore, this is only an issue when I play Spotify directly through Alexa.  When I play these songs just on my app on my phone (so not Spotify Connect to the Tap), or strangely enough, when I connect to the Tap via Bluetooth, I do not have this issue.  I can play all the songs on my playlist.  

This is a frustrating issue because it reduces the convenience of having the Amazon Tap when many of my songs will not play through the Tap when I use Alexa.  The connection between the Tap/Alexa and Spotify was one of the reasons I went to Premium, but this reduces the benefits of having Premium and I might switch back to Amazon Music.   Please help!

Screenshot of the issue