I take it back. I had a look at my e-mail and as it turns out I did manage to check in online for the US-originating flights on the last two occastions I flew IB out of the US. Last year I flew ORD-MAD-FLR in paid J and MIA-MAD-FCO in paid PE, and I did manage to OLCI for both itineraries in Chicago and in Miami on the day before departure. I had the paper BPs issued for all segments at OLCI and sent to myself by e-mail. However I could not get digital versions for the ORD-MAD and MIA-MAD segments for my iPhone, so since I didn't have a printer handy I had to stop by the check-in counters at ORD and MIA in order to get paper BPs. OTH getting digital BPs for the MAD-FLR and MAD-FCO legs on the same PNRs wasn't a problem. So it looks like IB does allow OLCI out of the US but it has a problem issuing digital BPs for the US-originating flights, for whatever reason..