Hi Lasse,
Simply clear your credentials and cache for Excel and try again.
Or simply you can copy fields from Gen. journal using Ctrl+C into Excel.
Make changes to field values in Excel and just copy the row from Excel and paste in Business using Ctrl+V.
This could be workaround but you need to evaluate if you Excel has any issues or exceptions created by something.
You can also create a Microsoft Support if this issue is critical.
Hope this helps!
