Remember when you model in Advance steel you have to be persistent in modeling your elements form left to right. Proper procedure dictates that you should always try and have your system line at the top of the beam and in the center of HSS items.
Run an audit checking for your project. You can use the AutoCAD tool Overkill to remove any duplicate objects, lines ....from your mode.
If this does not solve your problem, copy (Ctrl+shift+C) and paste (Ctrl+V) the model into a new drawing of the same template. Make sure your orientation corresponds.
Save this model over the problematic model. Never work from a drawing that has crashed always save as, and overwrite the original.
I hope this helps.