When opening the CSV file by double-clicking, Excel formats time without seconds by default. Change the formatting of the column „timeStamp“ according to the pattern „TT.MM.YYYYY hh:mm:ss“ so that you can also see the seconds. Here you will find step-by-step instructions.
Do not open CSV files by double-clicking, but use the import function of Excel. The import settings should have the cell type Text, not Standard. Also select semicolon as separator and UTF-8 as character encoding.
You can find a more detailed guide on that topic here: