I’ve tried this on tiffs and raw files from a few different manufacturers and result is always insanely contrasty and completely blown out highlights. Absolutely nothing like what Portra looks like. I’m confident this isn’t just a matter of opinion or interpretation of what Portra should look like, since other films that are known to be more contrasty work just fine in Filmpack. Unfortunately there’s no way to report a bug in the app so I’m posting here instead.