are you trying to do this all as beams or do you want to use some solids?
my suggestion is you start simpler, start with a few members, get that to work then add more until you get the whole structure
the model needs a bit of work to be a full beam or mixed mesh study but it depends on what method you want to use
I'm trying to do this all as beams, like I already do something similar in the past.
As you said, I'll try simplify the structure by cutting some elements and run.
I'll let you know as does it work.
I have faced the same problem before. The mesher fails saying there is interference but when I check for interference there is none. Switching the mesher and playing with the mesher setting helped me. Atleast, in my case I was not able to find anything wrong with the model.