I don’t think the persistence config works recursively. Given your Items above I think your persist config would only save the aggregated state of the Group grErdgeschossTEMP_SENSOR. You would have to either add temperature_erdeschossbuerobuero to grBaseTEMP_SENSOR or add grErdeschossTEMP_SENSOR* to the .persist file.
Personally I recommend creating separate persistence specific Groups and add all Items you want to persist to these special groups in addition to other groups you may have for other purposes. See the following:
That is true but the only “item” in grBaseTEMP_SENSOR is grErdgeschossTEMP_SENSOR. I don’t think is recurses into subgroups.