--days 1 --offset 1 (expecting day one)
--days 1 --offset 2 (expecting day two)
--days 1 --offset 3 (expecting day three)
...
That is different to our interpretation of the XMLTV spec & grabbers.
It would have worked if instead it used:
--days 1 (day one)
--days 2 --offset 1 (two days but skip day one)
--days 3 --offset 2 (three days but skip day two)
...