Copying picture-field in Workflow to another module is not working

hi community,

if I want to transfer the picturefield via workflow from cases to products the picture is not shown. If I go to the edit view I can see the right link-text, but when i klick on it, the picture is emptry.

url, of the product-module: entryPoint=download&id=945a4728-e154-f249-f762-5b683ca37afb_nachweis_c&type=AOS_Products&time=06.08.2018%2014:20

Version in 7.10.7

please help me