objects becoming transparent after saving as.ai

issue persists with several files, if I make anythign transparent, even if on its own layer, save the file as .ai and then reopen it, random items are compleetly transparent. text, objects, clipped images etc. if I then copy ANY item from said file to a new file even if not transparent, the issue persists. I cannot find a ryme or reason to it and need to know how to fix this. I've tried new files, un/reinstalled AI.

when I save my doc. all transparency settings are greyed out.

please help - this is causing hours of rework when up against deadlines - images attached.

 I am also getting an error within AI while working on a doc that is new after just creating type wihtin a box, it tells me it was created with a different version of AI, though its the same doc and the type was just created moments before.