Same error here. Hope this helps somebody from Apple to fix it...
DevTools:
URL main.711bbc1a.js:2
PATCH https://appstoreconnect.apple.com/iris/v1/apps/1644160287 409
{errors: [,…]}
errors: [,…]
0: {id: "58afe58c-9224-46f1-bfb0-8cfb1824a088", status: "409", code: "ENTITY_ERROR.RELATIONSHIP.INVALID",…}
code: "ENTITY_ERROR.RELATIONSHIP.INVALID"
detail: "PriceTier with id '0' does not exist."
id: "58afe58c-9224-46f1-bfb0-8cfb1824a088"
source: {pointer: "/data/relationships/priceTier/data/relationships/priceTier"}
status: "409"
title: "The provided entity includes a relationship with an invalid value"