When a curtain wall is placed below storey 0, it cannot be selected. I put two curtain wall, one on storey 0 and the other on storey -1. I then put an elevation marker in front of them. I viewed the elevation marker then select all curtain wall. Only the curtain wall on storey 0 is selected.
This is both on elevation marker and section marker. ArchiCAD 19.
~ReignBough~ ARCHICAD 24 INT 4018 FULL (from AC18) Windows 10 Pro, Intel Core i7-4790 CPU @ 3.60GHz, 32.0GB RAM, 64-bit OS