Load1+enun loads new units, while load2+enun loads party units. Perhaps you killed off your units in the end event for the 1st chapter? Clear all units won’t kill them, but disa on units will.
Icons click yellow circled thing and add new ones. All items follow the same palette.
In feuniverse discord there’s a help channel for questions like this if you need it. You can also send a report.7z if you’re stuck on something and someone will usually get back to you the next day.
See this thread for report.7z details or join the discord.