When you imported the credentials.csv file into Bitwarden, did you specify the File Format to be “Dashlane (csv)”?
Also, what version of Dashlane are you using? Bitwarden’s Dashlane importer is current as of October, 2024, so if Dashlane has introduced any format changes to their CSV exports since then, that could be causing problems.
Please open your credentials.csv file using a spreadsheet app (e.g., Excel) or text editor (e.g., Notepad), and copy the first row (which contains only column headers), and paste it into your response. In addition, if you opened the file using a spreadhseet app, please make a note of whether any of the columns are blank (no data below the column header).