Had a similar issue when attempting to import information in August; here's some information I posted elsewhere on this site that may be of help.

Blackbaud's undocumented encoding (both for import and export) is ISO-8859-1; Windows' ANSI encoding is an offshoot of ISO-8859-1, and the encoding is known by other names as well.

Note that Google Sheets (at least on a Mac) defaults to UTF-8 encoding, so an export from Google Sheets will need to have its encoding changed to ISO-8859-1 in order to import into Blackbaud with accents intact.

IMPORT TO BLACKBAUD

From Windows:

1. Open your CSV file in Notepad, which will automatically detect the correct encoding, unlike Excel);

2. Select "File > Save as..."

3. At the bottom, where the "Encoding" drop down is, select "ANSI" (this is Microsoft's ISO-8859-1, and seems close enough to be usable)

4. Either save over the existing file or enter a new name, make sure your File Type is "All Files", include your .CSV extension and save it as a new file

5. Upload to Blackbaud for import (and hope they haven't changed the format or messed it up in a novel fashion)

From macOS:

1. Open Terminal

2. Run the following command:
   iconv -t ISO-8859-1 {your CSV filename and path} > {new CSV filename and path}

3. Upload to Blackbaud for import (and hope they haven't changed the format or messed it up in a novel fashion)

EXPORT FROM BLACKBAUD

On a Windows system, you shouldn't have to do anything; Blackbaud's standard encoding should work just fine. (If this is not correct, drop me a note and let me know!)

If you want to import into Google Sheets, Blackbaud's standard encoding also works...because Google Sheets checks the encoding of the file before importing it.

On a macOS system, Numbers will also auto-detect the encoding properly.

With Excel for Mac:

1. Open an empty spreadsheet file

2. Select "File > Import"

3. Select "CSV", then click "Import"

4. Locate and double-click the Blackbaud export file

5. At "Text Import Wizard - Step 1 of 3", select "File origin: Windows (ANSI), then click Next
   NOTE: Western (ISO Latin 1) or Western (Windows Latin 1) will also work; however, "Macintosh" will NOT...and of course it can't auto-detect.

6. At "Text Import Wizard - Step 2 of 3", select "Delimiters: Comma and click Finish OR click Next and make any additional changes in "Text Import Wizard - Step 3 of 3", then click Finish

With Terminal:

1. Open Terminal

2. Run the following command:
   iconv -t UTF-8 {blackbaud's CSV filename and path} > {UTF-8 CSV filename and path}

3. Import your data per your application's default methodology.

Credit to Stack Exchange, which provided many many clues to lead me to this solution.

This is a critical requirement for us.

The inability to import data with the correct spelling of a person's name adds hours of work and increases the chances for errors. Blackbaud serves and international community of schools and families from around the world. It's time to support them all.