I recently received a Roku premiere+ model 3921RW. I plugged it into my 10 yr old Vizio TV, by way of HDMI, and could only get the boot screen(dancing Roku logo). After reading of similar issues with already working units, that were "fixed" with a firmware update, I hooked the unit up to another TV without issue and ran an update. I then reconnected the unit to the Vizio TV, and it worked. Unfortunately, I can only get a stable image in 720 mode. Even though the Roku states 1080p is available with HDCP 1.4, the image displayed drops out to black every few seconds. This of course makes 1080 unviewable.
I spent the better part of a day trying the suggestions on this forum( power cycling, plugging/unplugging cables, auto refresh rate turned off, same response on all HDMI ports, etc.), and can only conclude this is some sort of software issue. Until the update to 9.2, the unit wouldn't work AT ALL on my TV, and I have a feeling I'll never see 1080 till some firmware change fixes it. I assume it has something to do with backwards compatibility, but who knows?
If any Roku staff is reading this, and cares to respond, I'm happy to provide any more info needed.
Thanks in advance,
Display: Vizio Model#voj320f1a
Roku device: Premiere+ Model#3921RW
Software version:9.2.0:4806 (Hidden menu shows version 919.20E04806A build date 20191203)
@drezed Thanks for the note here. Have you tried using an entirely new HDMI cable with the device? It's possible that the cable has incurred minor damage, or is encountering an issue that only presents when higher amounts of data are being transmitted over the cable (1080P). I would recommend starting there. If that doesn't clear up the issue, please send me a private message with your serial number from Settings>System>About, and the specific model of Vizio TV you are connecting the device to. I'll follow up directly to see what else we can do to help.
As it turns out, I was able to resolve the issue by powering everything down, flipping the HDMI cable end for end, power up TV then power up Roku. After that both manual, and auto resolution work now at 1080p. I'm not sure why this made a difference, the cable doesn't appear to be directional, and I had performed the power cycling MANY times before. In the end it's working, so there you go. :-)