I travel frequently and have because of similar issues frequently (over 90% of the flights) an issue with international online check in as well as self kiosk check in - but at a traditional counter - never had a problem. I stopped trying this and are now going straight to the counter. So my experience with the 90% may be a bit dated.... but the last time I did a domestic check in attempt on the kiosk in May id did not work again .. so straight to the gaste is it for me