Don’t know what has changed in Deepin, but if you add file ~/.config/autostart/welcome.desktop with this contents:
[Desktop Entry] Exec=eos-welcome NoDisplay=false Type=Application X-GNOME-Autostart-Delay=3 X-GNOME-Autostart-enabled=true
it seems to start. Note that I’m not using Deepin, so this might not be the full answer.