Filter doesnt work

Hi , I m using office 365 on windows 11. 

When I filter my data and try to select the data I want to be shown from the dropdown , the filter just checks the (show all) box and instead of showing me only the data I chose, it shows me all the other data in the filtered cages except the one I selected. 

I tried to reinstall the application but it didnt fix the problem . 

I m sorry for the inconvinience in thepictures below but I use excel in Greek . 

1. Some filtered cages2. Normal dropdown3. only selected the checkbox before "b" value4. The result. "b" is missing