We recently tested creating a proof from both a standard workapp as well as the portfolio workapp that control center creates. I can upload the file from the standard workapp, but the invitation process does not work. I can fill out email and subject, click invite, but nothing happens. From the portfolio workapp, I can upload and invite someone to a proof with no issue. Also just as odd, the proof icon is missing from the row in the navigation bar, yet it's present on the right regardless of browse or workapp. Another limitation with workapps?