Unfortunately no success. I checked the Workbook settings; Tab Variables: Process Variables on refresh is checked. Exits: Do not run macros on Refresh. General: No refresh of Workbook on open.
In my case (workbook updated from BW 3.5 version) there is no CustomXMLPart(4) in the hidden sheet but the script(1) on the hidden sheet contains the data. When I save (also Excel generic save) then this script is updated (and contains actual data), otherwise it may be outdated.