Follow these steps to troubleshoot a Power BI date slicer:
Check the Data Type of the Date Column: Verify that the date column is properly recognized as a Date type in Power BI. Sometimes, the columns get imported as text or numbers, which does not allow the slicer to work properly. You can check this in the Fields pane and change it if needed.
Confirm the Date Table and Relationships: If you have a custom date table (recommended especially for time intelligence functions), mark it as a Date Table. To do this, go to the "Model" view, select the date table, and then under "Table tools," click on Mark as Date Table. Also, ensure that correct relationships exist between the date table and your data table. If any relationships are missing or incorrectly defined, then the slicer will not be able to filter data as expected.
Look through the DAX Measures: If DAX measures involve some date columns, make sure they refer rightly to the specific date column from the relevant table in the DAX calculations, particularly when there is more than one date column in play. Filtering on the date field may not connect to the slicer within the data model.
Review the Slicer Settings: Investigate the slicer itself. Make sure the slicer is properly configured to the correct field (e.g., the date field) and that the slicer type is appropriate (e.g., drop-down, list, or between). If it is for ranges, ensure that the slicer is set to show the right range of dates when viewing them.
Check Out the Missing Dates or Missing Gaps: Sometimes, the absence or poor completion of some dates in the database leads to abnormal slicer behavior. Ensure your date table is complete for every other date you are expecting, such that there are no gaps or unanticipated null values in the date columns of your dataset.
Confirm Date Granularity: If you are working with hierarchies (for instance, year > month > day), ascertain if the slicer is correctly set for the granularity you may require. Sometimes, complications arise while filtering at a higher level date, say a year, while the slicer shows day input.
Test Slicer Across Different Visuals: If the slicer works for some visuals but some don't, the problem is likely to be associated with the individual visual's interaction settings. Go to the Format tab, select Edit interactions, and make sure the slicer is properly set to filter the relevant visuals.
By following these steps, you should be able to determine the cause of the data slicer problem in Power BI and figure out how to fix it.
