Ive had few issues with OLCI. For trips to the UK, sometimes the app works, sometimes it doesn’t. In any case I have to show the passport anyway, at the gate like everyone else. Once in the AC I was asked to show it before I got to the gate.

However, I travel with firearms domestically: DCA-DEN quite a bit. On some trips, my record is tagged for the return as though I will be declaring a firearm on that leg. Even if I am not, I cant check in for the return via the app or online.