I'm having the same problem with an Apple TV 4K 2nd gen on tvOS 14.6 and macOS 11.4 with Xcode 12.5.1. Both are connected via ethernet to the same switch. (My AppleTV is named "Office") Hitting play in Xcode results in dialog "Office is not connected". Sometimes the Devices and Simulators window says "Office is locked". I often can go into remote app and devices settings on the AppleTV, see "Office" in Xcode's Devices and Simulators, click Pair, and entering the code correctly pairs so I can run. (I didn't unpair on either end.) But sometimes I get stuck where entering the code just shows the "Pair with Office" button again (no error). The only way I was able to break out of that cycle was to: restart my mac power off the tvos unplug and replug the tvos power cable start up xcode again and connect. I didn't even have to pair, so maybe there's an issue with unpairing? Regardless, building for tvOS is a really rough workflow.

I figured it out: I was giving transporter connected Arabic characters. I'm using Konash/arabic-support-unity to support Arabic in Unity and I'm applying it's ArabicFixer.Fix() when I load my strings. That replaces Arabic characters with connected characters so they display correctly (because Arabic is cursive). However, AppStore displays Arabic text correctly so it doesn't need any conversion. For some reason it gives this incredibly unhelpful error message (maybe because it disallows some unicode ranges). The correct text I should provide to transporter was: "أكواد الأصدقاء لإرسال الدعوات إلى الأصدقاء" (Which looks the same here because this forum connects the characters properly, but paste it into a dumb text editor and you can see the difference.) The Fix: skip ArabicFixer.Fix() when loading strings to populate transporter's What's New xml. That way AppStore can handle displaying the text right-to-left and connected. Instead, I give it the same strings provided to me by my translators.