Beam Definition won't apply to a few specific beams

I have looked everywhere and can't find a clear explanation of the mechanics behind when it will and won't apply the beam definitions. Apparently the pattern is acceptable, there were no errors when creating that, but the first 3 or 4 spans, the left most beam refuses to be created. Some of the spans it will let me select a beam definition and list it as such in the Beam Definition window, sometimes it won't even let me select a beam type, it just defaults back to the WF66G beam, which doesn't show anyway.

I would love to know the reason for why these beams won't create - given there is no explanation for it I've been trying all sorts of adjustments with no luck.

If anyone can help explain it for me or point me towards somewhere that might help me figure it out I would be appreciative. Thanks.