Issue ELM is sometimes not updating contacts it creates new ones
we have the following problem. We have a list in ELM which contains ORG ID and contact ID. In additional it contains Name first; last name; E_mail adress and a set of marketing attributes. When I run the list with 651 eintries ELM creates in some cases new contacts instead of updating the existing one. All other contacts are updated properly.
When I then go to Tx BUPA_DEL delete the new ones and again run ELM with only the new created contacts inside the list ELM is updating the existing contacts and is not creating new ones. So it is shure that not the data contains any errors.
Any ideas why ELM is doing so?