This didn’t work for me, but what actually did fix it for me was changing the setting at the bottom of the Pixel Streaming menu: I changed it from MP4 to another codec and then it worked. So this is a workaround for people where the fix above doesn’t work. (OP maybe you could add this to your solution so it’s easily seen by people facing the same issue)
Also, @shauncomly please take note - for me MP4 didn’t work which is the default setting. Only in 5.4, the whole setup worked in 5.3 with the same devices.