I have had my Roku Ultra for over a year now, it was working perfectly until the latest update in April.
I have my Roku hooked up via HDMI to my a/v receiver and my a/v receiver outputs the video back to the tv.
TV: Samsung UN55JU6500 Receiver: Denon AVR-720W Roku Ultra 4660X - Softare version 9.1.0 build 4068-46
When I turn on the Roku now, all I get is a black screen. If I try to unplug the power and reconnect it shows the dancing Roku splash screen then goes black again. If I hook up the Roku directly to my TV it works, but the whole point is to connect it to my receiver so I can utilize my surround sound system. I have contacted Roku support via email and they have been utterly useless. They keep copying/pasting generic info about how to hook up a Roku and telling me to unplug and replug the devices. I've tried that! That's not the issue, something from the new update is preventing the Roku from properly outputting the video signal.
Thanks for letting us know what you're seeing here.
Have you tried changing the display type to a specific manual setting while connected to the TV, then connecting the device to your A/V receiver again to see if this restores display functionality? Go to Settings>Display type and try selecting different options while connected to the TV, then connect the HDMI cord to your receiver and see if any of these resolve the issue.
Please PM me with your Roku account email address and any additional details or observations. I'll follow up with you directly to see how else I can help from there.