(I've found lots of posts about 2D cad links that disappear, this post is about Revit links that disappear.)

One of our Revit drafters is working in a project with a number of linked Revit projects of surrounding buildings. Each linked project is in its own workset. When she opens the project one of the buildings, always the same one is not shown. We have checked and

* the workset holding the link is open (Collaborate > Worksets)
* the link itself is loaded (Manage > Manage Links)

When she reloads the link it becomes visible again for about 10 minutes. She reports that it does not disappear in connection with Synronize with Central.

Any ideas what's going on?