Same thing is happening to me with my first ever app. Did 4 uploads, first two were having signature issues and are invalid, but the last two are stuck to In Progress, one for 12h and the second for a couple hours (8baacb91-71e6-4aee-8b7b-4e9e2737fccb, 0dfaf8f6-7108-44ec-94e0-0a25cd70b45f).