Revit Steel Connections going haywire

[basakbc007]

So I designed a couple of trusses with revit and used the steel connections to add some details.
Everything was going smoothly and I was happy with the results. But suddenly Revit decided to act strange and the trusses messed up, even the structural steel connections were not showing up in the type selection panel even when I deleted and tried remaking the connection. Its like revit stopped recognizing the steel connections although I had done them a couple of hours back. Also notice how the trusses look different with lots of overlapping intersecting lines between the members. Can anyone please enlighten me? 

[basakbc007]

So this is one building from a campus that I am designing as a part of my educational thesis.
And I have linked the building to the master file containing links of other buildings in the campus. Now I need to export the master file onto lumion to render some views. BUT. lumion live sync is simply exaggerating the master file to 4.5gb which is more than my system can handle. So as a roundabout I am using Simlabs trial collada exporter which keeps the export file size to 850mb which is manageable. everything was alright before I made this particular set of steel connections( mind it there were steel connections in another building also, but exporting that hasn't been any problem so far, but with this new set of connections, everytime after I export this problem starts occuring, steel connections disappear and steel SHS columns and beams get replaced by thin lines!!!!!! this keeps recurring again & again again. 
If you ask me why I dont stop after getting one good export, well, being a student of architecture, changes are inevitable and it seems revit won't allow me to change anything without messing up. PLEASE HELP!!!

[barthbradley]

You can post your files here for us to look at and troubleshoot. Or we could just blindly start shooting and hope we hit something.  😉   

[ToanDN]

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