Relative Date Filter suddenly stopped working

Good evening, 

Thank you for your reply. Unfortuately, it does not resolve the matter. 

• Relative date filtering only works when the target field is explicitly of type Date or Date/Time. Even if the column type is correct, the table needs to be marked as a Date Table in power bi. - We are aware and we built multiple functioning dashboards. But as said, from one day to another, all visuals using Date filters are corrupted and no dashboard is useable anymore. 
• If you are using the power bi service, the session or cache issues may prevent filters from applying correctly. Clear the browser cache and try using Incognito Mode and also test it in a different browser. - we are using PowerBI Desktop.
• A failed dataset refresh may cause the filter to return no values. Try a manual refresh and confirm that the data is loading correctly or not. - I did not mention any issues to refresh because there are no issues with refreshing. Hence refreshing does neither cause nor solve the problem. 
• In some cases, the existing relative date filter or slicer gets corrupted after updates. Try to remove the current relative date filter/slicer and add a new one using the correct date column. - It does not matter what we remove. The moment we apply a date filter to any of the visuals in any of the dashboards with any data source, the visual crashes and gives us the following helpful error message: 

"Unexpected error (file "", row , function "").

• Also there have been recent reports where relative date filters stopped working due to some backend changes in power bi service.  Check if there are any known issues. - No issues reported mentioning the date filter. 

Unfortunately no dashboard can be used anymore, the problem persists and management is already about to dump PBI for it.

So maybe someone has some good idea, what could be causing the issue?