List is empty with Provide Information action

I am creating a service to stop a running VM. A runbook will retrieve a list of running VM's. This list is stored in a service attribute. With the provide information action the user can select a VM.

However, the provide information page shows empty values. The count of the empty values equals the count of the list.

Please help!

I assume the list has a format of 'value ; value ; ' etc. I also tried the format 'value ; description | value ; description |' but getting the same results. The last one seems to work in a previous version

Regards, Marcel