[itsme]

The preconditions for a successful CSV import are:
1.) CSV and PDF file must have the same filename (Except the extension) e.g. MyFakebook.CSV and MyFakebook.PDF
2.) CSV and PDF file must be in the same folder on the tablet
3.) semicolon must be used as separator in the CSV file
4.) The first line of the CSV file must contain the column titles for the metadata items to be used e.g.
title;pages;keys;source types;composers;years;tempos;signatures;albums;
5.) "title" and "pages" are mandatory, all other columns are optional
6.) all lines of the CSV file must contain the correct number of separators

Android and Win10 UI are slightly different:
on Android you just open the CSV, the PDF is found automatically via the matching filename
on Win10 you select the CSV first, then, in a second step, you select the PDF

@chrisss: I shared folders of my GoogleDrive with some examples with you. If these examples do not answer your questions, send me a pair of files that demonstrate your issues . I'll take a look at them and I'm sure I'm able to fix the CSV.