Answer:
The "Convert Area Loads to Member Loads via Plane" load generator is basically only intended for members in a plane, and thus works best. For structures where the members do not rest in a plane, but in the individual areas, the "From Area Loads on Members via Cells" function is the better choice. In this case, you can use dummy members to create closed cells consisting of three members, which can then be subjected to loading.
Otherwise, the tolerance settings would be a solution. They allow you to also define members outside a plane. You can define the details as shown in Image 01.
More information about the load generators can be found in Chapter 11.8.2 of the manual.
![Spans Based on Figure 5.2 from [1]](/en/webimage/039540/3493372/01_Abmessungen_EN.png?mw=512&hash=3cc425f1463bd5981b358d5889e3109e07ae1233)
