I am trying to check in for a BA flight. it's BOS-LHR tomorrow, followed by LHR-GVA the day after. But, OLCI fails saying "Sorry we can't check you in for this flight. Please go to the airport check-in desk." I feel like I am hitting an issue mentioned in this guide -
" Is your second flight on the next calendar day?"
But, I see no way in the app, or online to select to check in to only the first flight. Any advice on how to do this?