Hi,
This sounds like the value entered under the column of the characteristic in your CSV doesn't exist for that characteristic in the HikaShop backend.
For example, if you have an extra space at the end of the value for that characteristic, this could happen. And in that case, since the system can create the variant, but doesn't know to which value it should assign the variant for that characteristic, there would be no value displayed in the column of that characteristic for the variants with the issue.