Hi Philipp.
I have experienced the same problem. The final solution was to protect the epm sheet with the following macro (not manually, via the Ribbon Interface):
Public Sub Protect()
Dim api As Object
Set api = Application.COMAddIns("FPMXLClient.Connect").Object
Dim SheetProtectionOptions As Long
SheetProtectionOptions = FPMXLClient.ProtectSheet_ProtectContents + FPMXLClient.ProtectSheet_UserInterfaceOnly + FPMXLClient.ProtectSheet_AllowFiltering
api.SetSheetOption Sheet1, 300, True, "YOUR_PASSWORD", SheetProtectionOptions
End Sub
Check the chapter 41.2.3.1 Sheet Options, of the EPMofc_10_user_en.pdf, for other sheet protection options.
Best regards,
Marco