CARDAV: Selfdefined Labels for Phone Numbers within contacts are messed up

I use CARDDAV with a baikal server for my Contact. Everything works fine so far.
The same server is also used by my iDevices.
When I use selfdefined PhoneNumber (e.g. Administration) it is being synced as “Administration” to the Server. When I change anything in that Contact on my iDevice the changes are correctly synced back to server. But eMail-Client changes that “Administration” to “ITEM_1”…
This is really annoying.

Hello,

We’re very sorry for the inconvenience. In this case, we would ask you for advanced logs to be able to examine the issue more closely. Please go to Menu -> Tools -> Settings -> Advanced -> Logging and turn on logging for ‘CardDAV’ for the relevant account. Reproduce the situation and turn eM Client off. Afterwards please go to a folder where the logs are saved (default location is C:\Users\username\AppData\Roaming\eM Client\Logs), choose the log that has CardDAV and relevant date in its name and send it to hester@emclient.com with a link to this thread.

Thank you,
Maurice