Hi Peter,

following the beams rendering issue, I thought I might be able to see whether and where the problem is by running a modal analysis of the structure. The outcome does not tell me much new: the same beams appear also somehow "wrong-connected" from the rest of the structure but they don´t fly away either:

I doubled checked their connections with the rest of the elements and they look ok, much the same as the other equivalent long-beams which don´t pose this problem...:

So I don´t know what else to do in order to figure this out...