I am not sure that this is a problem with the save game, the only way to make sure is to use a other, much earlier save game or start from scratch.
This could be a hardware problem as well.
I encountered the same issue (minus the disappearing elevator). It was seemingly resolved after I ran a fix through origin (don't know if that's possible in steam), and made sure my mods were up to date (had to update the extended galaxy and audeamus' happy ending ones) and then the meeting with specialist Traynor occurred immediately after speaking with Liara, following the dream.
Don't know what helped, but my game is now no longer stuck, so I'm happy.
