At least every few weeks I get a call from someone asking why they can’t get Vault to appear in any of the menus within Inventor. One of the first things I check is if the Vault EDM (Engineering Data Management) add-in is loaded. This is usually the culprit 99% of the time.
Here’s a good post by Jonathan Landeros on how to make sure it’s loaded:
http://www.inventortales.com/2013/05/autodesk-vault-ribbon-disappears-when.html
Some forum fodder on the subject:
http://www.mcadforums.com/forums/viewtopic.php?f=5&t=12723
Jonathan said it best…
Every time I started a new component. My Vault ribbon would disappear. That’s right, just like Nightcrawler from X-Men, it would Bamf! out of existence.