This exact issue affects only users whose Trados Studio 2021 application is activated with a
subscription (not a perpetual license), and whose computers are not part of a
domain network. Sometimes when the application is restarted, some or all projects are removed from the project list.
This problem only seems to occur when the user is in the
Projects view before closing the application. Only standard local projects seem to be removed (cloud- or server-based ones, or projects originating from a package seem to be kept).