Having just done some further tests it may be that the mismatch of spaces between text file contents and the mask is also causing the issue.
Once you have made sure there are no Tabs then you will also need to reduce the number of spaces so they match your mask.
This is also very easy in Notepad++
Select all and using Replace (Ctrl H) enter two space's in the Find What: text box, make sure the Replace With: text box is empty and press Replace all and that should clear out any multiple spaces, leaving you something like this:
|19814121C.mp3 |Human League |Open your Heart |23 |11/10/1981 |21 ||
|19814123C.mp3 |Elvis Costello |Good Year For the Roses |8 |11/10/1981 |23 ||
It may or may not have spaces after each section and you will have to adjust the mask once you have done the removal based on what is produced.
I would recommend that you work on a copy of your master text file.
As a reminder each line will need to have the same format - so if you are left with some lines that have a space after the artist name (for example) and others don't then a further run will be needed.
In this case search for | (space bar) and replace it with | (just the bar). This should then make all lines like this:
|19814121C.mp3|Human League|Open your Heart|23|11/10/1981|21||
|19814123C.mp3|Elvis Costello|Good Year For the Roses|8|11/10/1981|23||
And adjust the mask accordingly.