The specific reason has not been found yet, but using PowerBi or using the following imported data can solve the problem;
1. Use PowerBi to import files (and then copy the table/use DAX to export data), so the method involves non-Excel software, so it is only for reference for the time being, and will not be described~
2. The solution to using Excel to import data (use environment: WPS -- official version on May 23, 2022):
# word description:
> - New Workbook
> - Click - Data Tab
> - import data
> - Import data (submenu)
> - OK Import
> - select data source (select file)
> - File conversion (other encodings, as long as the text below is displayed normally, generally the default is fine, no need to deliberately process)
> - next step (default delimiter)
> - Next (tick comma delimiter)
> - Click on the suborder number column (tick text)
> - Click on the main order number column (check the text, pay attention to whether the target area is the starting position you want)
> - click - done
> - Wait a moment for the data to appear in this Excel active sheet (wait time proportional to file size)
image description:
Finally, click Finish~ Wait for a while, the data will appear in this Excel active worksheet
(Waiting time is proportional to file size)