Thank you for your comments and reports here.
Right now we have an Ongoing issue with what you seem to be experiencing on your Amazon Fire TVs.
We'd recommend leaving a +Vote in our Ongoing Issue thread if you already haven't.
You can also subscribe to that thread via the three dot menu so that you'll be notified when we have any updates.
We'll be here if there's anything else we can do for you.
Have a lovely day!