Hello everybody!
Regarding to the missing audio with EyeTV iOS app (iPhone / iPad), I can confirm: It is a bug on the EyeTV 4 release 8526. Install release 8524 and the audio works when connecting to the EyeTV on the Mac via your EyeTV iOS app on the mobile device.
I informed Elgato support accordingly. As it worked on the previous release, they should be able to fix it.
Best regards, Roland
Where to find the previous release 8524? Just go to > Support > Software > eyetv 4 mac OS: Support. There you will find all releases down to 8518. Just go bach to 8524 and install it over the 8526 release. For me it just worked, even on a MacMini M1. Of course, like this you will lose the improvements that came with 8526, but at least the audio works.