Excel Values Uploading as NULL to database
Answer originally left as comments

This is a data type issue on Excel's side, and the file was probably created by someone else. By copying and pasting using Notepad, you're stripping all formatting and effectively converting the data types to strings. I'm betting it's a date field or a number that is being formatted in an odd way and the SQL implicit conversion is failing because of a leading apostrophe or something ridiculous. – Randolph West

Unfortunately, importing Excel data is rife with difficulties like this. You'd be far better off to get the source data in another format such as CSV, or better yet, a binary format of some type. – Max Vernon