In an excel file, the columns include name, age, gender, etc.

Now there are 800 pieces of data, including 20, 21, 22, 25 and so on. Now using the filter function, it is found that there are no 25 items in the drop-down list. The reason for this phenomenon may be that there are blank lines in the middle. For example, if line 600 is a blank line and does not contain any content, the filter only filters lines 1 to 600. At this time, the drop-down list only contains the age values that have appeared in the first 600 lines. After using keywords for filtering, 601-800 rows of records will also be displayed in the results. However, we found that the line numbers of the records filtered out from 1 to 600 are blue, while the line numbers from 601 to 800 are black. Therefore, the 200 lines are completely displayed there without any filtering.

Note that the blank line here means that all cells in this line have no values, or even spaces. Even if the value of only one cell in a row is a space, although it looks like a blank row, excel will not treat it as a blank row when recognizing it.