I noticed that event duration is 10 hours, but when you land on Yahoo Calendar page it turns out it's only 1 hour long.
This is probably due to dur parameter, which is five-digits long (01000): setting dur=1000 the duration of the event seems OK.
https://calendar.yahoo.com/?v=60&view=d&type=20&title=DIGITALEROSA+2017+-+l%27Evento+di+Formazione+con+le+Donne+del+Web+Marketing+Italiano&st=20171111T083000Z&dur=01000&desc=For+details,+link+here:+https://www.eventbrite.it/e/biglietti-digitalerosa-2017-levento-di-formazione-con-le-donne-del-web-marketing-italiano-28695064711&in_loc=Environment+PARK+-+Via+Livorno%2C+60+-+10144+TORINO+-+Italia