It is a known issue in the C8030/8035 firmware , and oddly, just that one (It isn't an issue with the 8090/8070/8055/8045)
They (Xerox Engineering) are currently still working on it.
I don't have one to check, but the SPAR escalation on it mentions the EWS/CWIS page in the description, which may mean it works when done at the UI (Log in as admin, select Customize and then drag an Icon)
Please be sure to select "Accept Solution" and or select the thumbs up icon to enter Kudos for posts that resolve your issues. Your feedback counts!