No nap for me this afternoon, but when reading the answers in this Conversation, something comes back to my mind: a bug of mine…
In a Listbox, I change the number of Columns at Insert time, then add some row(s), and a following addition (Paste) I noticed a miss in the number of columns. I added some columns and my data went back.
If in your data (the data you want to Paste) you have an EndOfLine (Return, LF, Enter, whatever), you will not be able to watch anything but an empty line.
To check that, set your Listbox to all columns Editable(s) by a simple click (or a DoubleClick), and try to edit one of the “empty Cells”, place the cursor at the end of the Cell contents, then press the Delete key and watch carefully what happens…
Of coure, Tim is right: it is not easy to make diagnostics without seeing the project.
Back to the number of columns: when you change the number of columns of a Listbox, you do not delete the contents of the Listbox, you only display that amount of columns; if you change the number of colums back to the original number, you get your previous data back on display. (provided you do not delete the previous Rows / close the window, etc.