Values in multi pick list are not copied to copied deal

Values in multi pick list are not copied to copied deal

Hi,

After a deal is completed in our sales funnel we copy the deal to an automatically created new deal in our project funnel. All fields are copied properly, but only a Multi Pick List is not copied. How can we copy the selected values in this field also to the new created deal (project funnel)?

Thanks in advance!

Best,
Jeffrey