Filter data table by date only filter some dates

Hi, after having extracted a table from a website (column by column and naming the columns, not as a full table) I try to filter by ascending date. That does in principle work, but only for about 60% of the rows/dates, the other remains descending as they are in the original table. All dates are formatted in the same way, and I am unable to find any differences apart from the date itself. What can be the reason for this?

Kindly have a view on this thread

Cheers @wwls

That is a slightly on the side from my issue. In my case, if the table has 10 rows, all identical in setup and formatting, 6 of them will be filtered correct, and 4 not filtered at all. So the question is, how come those 4 rows are not filtered when they otherwise is the same as the rest?