I've done just over 40 before. If you are getting line breaks and/or bad importing it is usually due to something amiss in a cell. Usual culprit is line breaks in a cell. Missing headers or illegal characters in a header can cause a breakdown at import as well.
I would recommend opening the csv in a good text editor to review the data for line breaks first thing. Oh, and I always use tab delimited as well. A misplaced or missing quote mark (iif used in the text of a cell can also cause an import failure.
Each line in a good Excel export when opened should begin with the data in your first column. If not, that indicates a line break in some cell.
Thanks very much for your reply. Good to hear you managed more than 20! I have tried to remove all the line breaks as I am aware this is the issue but can't see any. I will try another editor. All columns have headers and don't believe I have any illegal characters - only underscores and letters. I might try to rename just in case.
Good morning, Sue.
If you still experience issues, feel free to upload at least the test sample of the csv to dropbox.com or the like and PM me a download link and I would be happy to take a look.