Data loss when publishing to Service

Hi, 

I am using a Pro licence, for starters. I have a workbook that upon refresh does some transformations. Among others I am lookuping certain calendar values. The way I do it is that I am mergin a lookup table into the main fact table through a common key. 

As seen below the "Lookup.Combined" is the search key that connects the two tables together. 

The issue I have is also visibe on the screenshot - meaning certain values do not work - in this case 2026 is blank, though in the initial lookup table it is configured. 

The solution works on my Desktop. Meaning I get all the values to work. But as soon as I publish the report to Service and resfresh it in the Service, some values (for example this "2026") disappear. 

Many thanks in advance for whoever knows the solution 🙂