The manual export from Lotus Notes to CSV (which you can then open in Excel) is notoriously unreliable, especially with large databases. It often leads to formatting issues and data loss, as you've discovered.

A much better approach is to use a specialized tool designed for this. I had a similar issue a while back and ended up using the eSoftTools NSF to PST Converter. Don't let the name fool you; it does more than just PST conversion. It allows you to export Lotus Notes databases directly to a clean, well-formatted CSV file.

You can then open that CSV in Excel without any of the usual headaches. It saved me a ton of time and preserved the integrity of the data. I'd highly recommend giving it a look.

Read More - https://www.esofttools.com/blog/export-lotus-notes-database-to-excel-csv/
Website - https://www.esofttools.com/nsf-to-pst-converter.html