are you talking about the old fat client trays or the new web client baskets?
Personally, I have never worked with the old fat client. Regarding the new web client baskets, I have never seen or heard of this.
Maybe the Basket User accessed the configuration and changed access rights to the basket or deleted the basket (in case he had configuration rights)? Can you still see the database table for this basket (if on-premise)?
Greetings from Germany,
Simon H. Hellmann
DocuWare System Consultant