I got 50% of the Zygarde Cells and Cores, Sina called, saying to meet at the Aether House, but when I went there a bit later, they weren't there? Did my game glitch, if not, are they somewhere else? What happened?
You need to go to the Aether trailer in front of the Pokemon center on Route 16, not 15. Inside, there is a Zygarde cell rearrangement thing and Sina and Dexio should greet you inside.
Hope I could help