I'm experiencing the exact same issue described in this thread. TestFlight installation fails for ALL apps under my team with "The requested app is not available or doesn't exist" — for internal and external testers alike. Builds show "Ready to Test" in App Store Connect, re-uploading with new build numbers doesn't help, and this affects apps that were never part of any transfer, not just the transferred one. This started immediately after receiving an App Transfer from another developer's account. My support case ID is 102939200882, currently unresolved after 10+ days. I had a scheduled phone callback where no agent joined after 35 minutes on hold. Given how many of us are reporting the same pattern (account-level TestFlight failure following app transfer), could someone from Apple engineering please look into whether there's a common backend issue affecting teams that recently received app transfers? Any update would be greatly appreciated.