PP can be frustrating, especially when young developers insist on including commas (and even currency symbols) in number fields to ensure there is no rounding. Another joy I’ve learnt with European software is they reverse the thousands and decimal separator characters, so they can’t use a comma in the csv and use a semicolon instead! (Seems ‘C’ doesn’t translate.) And dates, well that’s a whole new forum!!
It does work but you need to be careful. My tip is try Tab delineation because it is easier to visually scan the document. If you want to use comma separated variables (CSV) then do a quick delete of any thousands separators or ‘$’ characters in the data.
None of this is a problem once you understand how to work with it.
If that doesn’t help, more information is needed. Create some dummy data (or grab it from Import CSV file or Reporting Across Multiple Security Accounts - #6 by flywire) and give us an example. An example would be handy for anyone reading this post later anyway.