We're currently aware of a bug where cone targeted abilities (e.g.: Annie's Incinerate, Nidalee's Swipe, Kassadin's Force Pulse, etc) are reversing their direction when cast **immediately** after using another ability (e.g.: the Flash Summoner Spell, Nidalee's Pounce, Kassadin's Rift Walk).
Champions who rely on cone targeted spells to finish their combos are most impacted by this, like: **Nidalee, Kassadin, Pantheon, Annie (Flash + W), Darius (Flash + E), Singed (Flash + E), Riven (2nd cast of R), among others.**
We're currently tracking this to find a proper fix (due to the nature of the bug we can't make any promises on a timeline) but, in the meantime, the best workaround is to slightly delay your cast combinations to accommodate.
Sorry for the inconvenience!