Testcase import (XML) does not import all fields

I'm experementing with Test Case import / export.
As I wanted to learn about the TC structre, I exportet Test Cases that are designed within Testrail.
Testcases with the most common fields like ID, title, steps, expected result, test data.

Now, when EXPORT this test case and afterwards IMPORT it to Testrail, for some reason Test Rail only recognizes ID and TITLE.
All the other fileds like STEPS, EXPECTED RESULT, TEST DATA seem to be ignored by the import process (although they are in the XML that was originally exportet from Test Rail).

Any ideas here ?