This probably indicates some corruption at some level.
If you create a new drawing with a new view to this assembly, do you get the same results?
If you find that it is with the assembly, you can do a pack and go on it and let me know and we can figure out how to get it to me to test it for you.
If it is corrupted in the view try recreating the view, but I expect that you have already done that.
If it is in the IDW/DWG, you will probably have to recreate the document.
Does this help?
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