I have a RokuTV 7303X (OS 9.4.0 Build 4200-31) and a MacBook Pro 13" 2017 (macOS 11.1 Big Sur).
I have rebooted both multiple times. I have verified both have an excellent Wi-Fi connection.
I can screen mirror from my MacBook to the RokuTV via AirPlay easily. The audio is constantly out of sync, but at least I can get it up there for my presentations (issue #1).
However, when I open a video in Quicktime on my Mac, it gives me the option to AirPlay it within Quicktime to my TV. I select this option. The video stops playing on my Mac and the RokuTV just shows the AirPlay screen that shows my Wi-Network and Device name. It doesn't actually play anything. No error messages. I've tried multiple times, with different videos, I can't get it to AirPlay from Quicktime. However, I can get it Screen Mirror, so I know it's connected.
I have tried going into AirPlay Settings, and have reset settings, repaired my Mac, and still it will no play any videos from Quicktime, it just brings up the AirPlay app with no video.
I had the same problem tonight when trying to airplay from a late 2015 27" iMac to a 2020 Roku Ultra running RokuOS 9.4.1 build 4236, and macOS 11.2.1 (iMac). Just got the Airplay settings instead of the video. What I thought might be wrong in my case was, it didn't work over a wired network since my devices are wired, and on screen it said to make sure they were on the same WiFi network. Since the other people here had the same issue on WiFi, it would seem that's not the problem. I do have a couple of Apple TVs that I could test, just to make sure AirPlay itself isn't broken, however a month or so ago, I tried AirPlay from an iPad / iPhone via the YouTube app and it seems to have worked. Also, Music seems to work via AirPlay.
I'm wondering if Roku's support is limited, and unlike the Apple TV, full AirPlay isn't supported. Has anyone been able to come up with a solution ?
Have you tried making sure that both devices you are trying to use for Airplay are on the same wireless network?
Please keep us posted what you find out.
Here is an update for you.
I have my devices all on the same LAN, and the computer, and streaming devices are all hardwired.
What I found out is, this is a problem with local playback from QuickTime player, and a third party program I use called ElMedia player. When I did airplay from safari, to Roku things played nicely from YouTube, and screen mirroring works as well.
I did further confirmation to isolate the issue to Roku and local airplay playback by doing the same thing with my physical Apple TVs and the Apple TV I used worked with local playback where as Roku didn't
I could play video to the TV via mirroring, but having the app send it directly would be a better solution.