Updating to 4.3 (I was on 4.2.2 previously) resolved whatever my issue was for my Verizon S4. It now works with both my podcast app, and Google Music (the one that matters).
I was actually still rooted when I updated, but I had to restore some files that had been modified (mainly framework files). But for your purposes: Updating to 4.3 did resolve my issue, the E18 now works with my S4.
There is at least one unconfirmed report that Jelly Bean 4.3 is helping with the USB host issue on the S4.
Hopefully I will be able to offer some more info soon. There are web-rumors that AT&T will be rolling out this update starting today. We'll see.