The only way we could reach your state described was by entering cell in edit mode and then pasting the content into it. In this case, the entire information that was copied from excel is considered as single value, and so, it is normal to place the information into one cell. Keep in mind when trying to copy/paste multiple values, you must have the cell selected, but not be in edit mode in that cell (edit mode is when the cursor symbol appears in the cell). One suggestion is to copy the information from column one by one.​