Data value is split into two rows/columns but counted as one distinct value by Power Query/DAX

Recently, I have been working with a data model, where I had to include data generated from a Microsoft List and append it to an existing table. This lead to some odd behaviour with the rows from the list, as seen in the picture below. It appears as if Power BI handles the values from the List-data separately from the other data despite using the exact same values.

In #1, PQ shows four values in [Kategori] in the table that is created by appending the List to the non-List data. There appears to be no issues here.

As seen in #2 & #3, when the data is then added to a table or matrix, the one value (= "S") that appears in both the List-data and non-List-data starts splitting off into multiple columns/rows.

Especially odd is the distinct count of [Kategori] values in #3's tables: here, the sum is still four both with and without [Kategori] as the dimension/attribute.

Is this a bug or am I missing something that causes this behaviour?

There were no issues prior to appending the Microsoft List-table to the original table - in fact, I had entered data manually in a separate table before deleting and replacing it with the Microsoft List. It seems to only be related to the List-data, as Measure 1 and Measure 2 calculates the exact amounts present in that data (6.200 and 1.550, respectively).