Chequered Pattern in Cells
The graphics you are seeing show that there is no source data for the cell. That is, the grid knows that there should be a cell there, based on the rows/columns, but does not know what the actual data is. Without having a source-row, the grid is unable to write data since it does not know the underlying key-fields for that cell.
Consider the following data:
If this data is used in our visual, then the visual can infer that there should be a "Palestinian Territories" for all employees, even though there is no underlying data for anyone but Adeline.
This means that all employees except Adeline will have some missing source rows, and thus chequered cells.
There are a lot of different ways to get Power BI to return rows for each cell. For the simplest of use-cases enabling "Show items with no data" might suffice. Other times, you may want to create a measure that controls which rows are shown or not.
It is best practice to create a measure which controls which rows are shown since it gives greater control & is easier to modify.
When creating a measure that controls which rows are shown or not, it is good practice to keep it separate from the measure which actually contains data. In the example above, we might want to return values for all employees, regardless of their territory. To do this, we'll create another measure that looks like this:
Then by dragging this value into the visual, we'll see that rows are shown for every combination, and that the chequered pattern disappears.
It is easy to see how this measure can be modified to return other rows too. For example those who do not even have any work hours planned but will need to be planned in the future.