Need help to fix a problem that keeps crashing the editor

[Solnear]

Hello everyone,
So when I try to add in any of the outer meshes besides the three sided outer mesh. I've send a crash report but I'm not sure if it just something that I'm doing wrong, if anyone knows how I can fix this issue it would be very very appreciated.
I'll also link some screen captures of the error messages and crash message.

Spoiler: Pictures