It can happen that contacts that have already been deleted are still in the journal of the clients. Although they are no longer available in any data source, they are still displayed in the "cache" of the so-called JournalAdapter.
How exactly something like this can occour is explained here:
To remove these contacts completely, a search in the journal must be started for the affected client(s).
To be on the safe side, we recommend to perform a search query for the phone number and a search query for the contact's name. Afterwards, all journal entries for this contact / phone number must be deleted.
Note: Multiple entries can be selected by holding down the CTRL key.