Hi SGIII
Based on your suggestions I have worked my way through different combinations of region and format settings.
And it seems the bug is related to Region as you suggested. Setting region to US, UK or Germany all works. Denmark has the bug and at least Norway has it too.
So if it is of any help to others this is what i did:
Original setting: Primary language: English. Region: Denmark. Format language Danish.
Changed settings as follows:
Region: United States. Default formats. : Result OK
Region: United Kingdom. Default formats: Result OK
Primary language: Danish. Region Denmark. Default formats: Error back. All numbers interpreted as dates.
Primary language: Danish. Region United Kingdom. Default formats. Result OK.
Primary language: Danish. Region United Kingdom. Format language Danish: Result OK.
Primary language: English. Region Germany. Format language Danish: Result OK.
Primary language: English. Region Denmark. Default formats. Error back