My iPhone12 can show Utube videos fine via my HDMI and monitor set-up but for some reason I can only get Zwift sound and no video. I used to be able to get Zwift to work this way but for some reason it has stopped working. Anyone had similar issues and aware of a fix otherwise I will have to find another fitness app to use.
I’ve not got this setup myself so can’t comment but I do know that the setup is possible/should work and that others are using it without issue. Which HDMI connector are you using, it it the Apple Lightning->HDMI adapter one?
One option if you can’t get it to work is just buy a cheap used AppeTV. They’re cheap as chips and having a dedicated device for it makes it a lot more painless.
I found a fix which is quite common for iPhones apparently: go to settings, general, airplay, switch automatically airplay to TVs to ‘Never’. If this is on automatic it can interfere (somehow) with the HDMI functionality. This is 2 hours of my life I will never get back. Happy NY!