I'm trying to use an embedded visualization in my web app. There's nothing fancy here. When the app loads, the viz loads nicely. When I make a selection, nothing occurs when I click "Apply Now". The values and the line chart don't respond. I've tried searching for an answer and found that I can use javascript to update the iframe, but in ES6, is that still the answer? Is this a bug on my end or something expected from embedding viz?
It's neither expected not a bug on your end. It's a bug on our end 
You can find and follow it under: https://github.com/elastic/kibana/issues/16595 Unfortunately the fix is not that trivial as it seems, why we couldn't fix it properly yet, sorry for that 
Thanks @timroes. Are there any suggested/preferred work arounds?
Sorry, we currently don't know of any possible workaround for that.