With the release of Eos v3.0, Eos includes a new Staging Mode, requiring replacing the "Scroll Lock" key with a new "Stage" Key.
This key is compatible with Ion Xe, Ion Xe 20, Gio @5, and some models of Gio, Eos Ti, and Eos Programming Wing.
Confused about which key you need? Use the tool at the link below to determine which key will work with your console:
https://www.etcconnect.com/Keycap-Selector/