Thanks for the comments. I'm getting this on both the app and website, and tried both different and private browsers. When doing GLA-LHR-VIE I can select business, but a few steps later I get the message about no business class on the LHR-VIE segments. However, when changing the search to just LHR-VIE there's no problem, albeit the cost is greater... I'll leave it for now and after restarting devices and clearing caches I'll try again and see what I get.