Hi Katja Tecklenburg,
We had some improvements on workbook conversion on the past 3 delivered patches.
To give you a correct answer we should be able to analyse you workbook because we had some corrections with formula conversions / conversion with macros / with descriptions with spaces / and also variable values do I believe that a simple test is upgrade analysis for office to SP10 and convert the workbook again before save on BIP.
You can check new versions by the links:
Analysis for Office versions Client 32 bit: https://websmp208.sap-ag.de/~form/handler?_APP=00200682500000001943&_EVENT=LIST&EVENT=LIST&ENR=67837800100200022686&SWTYPSC=SPP&PECCLSC=OS&INCL_PECCLSC1=OS&PECGRSC1=WIN32&V=MAINT&TA=ACTUAL&PARTNR=67837800102800428138
Analysis for Office versions Client 64 bit:
https://websmp201.sap-ag.de/~form/handler?_APP=00200682500000001943&_EVENT=LIST&EVENT=LIST&ENR=67837800100200022686&SWTYPSC=SPP&PECCLSC=OS&INCL_PECCLSC1=OS&PECGRSC1=NT_X64&V=MAINT&TA=ACTUAL&PARTNR=67837800102800428138
According to the error message WB42020 i could see that it can be related with the HTTP or HTTPS so you can check the SAP note 1955373 - Viewing Analysis Workbook/Presentation from BI Launchpad.
And you can also check the activation of InputFile and OutputFile services on BO server. It can also help.
Kind regards,
Diego Ferrary