There was an earlier discussion and a number of workarounds for some problems with the Harmony remote and the OK button not functioning in several apps.
I received a reply to my support ticket with Logitech this morning that they updated the Shield TV profile. I can confirm that the OK button now works in the Amazon app. If others could try the other apps listed in the "Problem apps" section of the above post we might be able to finally call this irritating one solved and get rid of the kludgy workarounds. I followed these steps which are mostly the same as listed on their website:
I didn't have to re-do the steps to pair the Hub with the Shield TV over Bluetooth since it still remembered the connection. Once I deleted and re-added the Shield I went straight for the Amazon app and had no problem navigating like I expected.
We've just published a massive update for Headlines, the RSS reader for Android TV, and Amazon Fire TVs (I hope we don't get in trouble for mentioning FireTV here), and we'd love it if you could give it a try.
We think this update really brings Headlines up to what we wanted for it at initial release. The interface has had a complete redesign, streamlining the interface and feed list, we've also added trending twitter hashtags for your locale, hourly weather updates, the ability to have the list highlight terms, and AMP site view for most sites.
If you'd like to try it you can grab a promo code here. If you do we'd love if you could submit a review on the Play Store, but that is in no way a requirement to get a code.
EDIT 23RD FEBRUARY:
As per feedback from some Redditors we have added DayDream mode, inline images to the feed, and made some improvements to the loading speed. These are included in version 2.1 which is syndicating now.
Bringing your favourite news to your big screen. Headlines lets you select your favourite sources for the news and displays the top headlines, refreshed every 10 minutes.
Combining the latest news from a variety of sources in 11 different categories with daily live currency rates, hourly weather updates, and current trending twitter hashtags, Headlines is the ultimate news rss reader for your Smart TV.
With in-line article view, now supporting AMP sites where possible for a fast and smooth experience, you can not only get the latest headlines but can also read the full articles on-demand.
Headlines is powered by RSS and Atom feeds straight from the source, and currency rates from the European Central Bank so you can guarantee you will always be up to date.
Designed with simplicity in mind, Headlines blends into the background with clear headlines to read at a glance. Now with added theme support, making sure you can choice a colour theme that suits your style.