I am trying to copy the content of a MUP of a parent issue to its linked sub-issue in a workflow's post-condition. Therefore, I was trying to use JWT's post function "Read fields from linked issues or subtasks". But my approach just generated the following error message.
"Error occurred while creating issue. This could be due to a plugin being incompatible with this version of JIRA. For more details please consult the logs, and see: http://confluence.atlassian.com/x/3McB java.lang.String cannot be cast to java.util.Collection"
The the parent issue "is blocked by" the child issue. Both fields are Multiple User Pickers.
My configuration was is set as it is shown in the screenshots (I just attached screenshots with fields that have been changed compared to the default settings).