thank you, it works, if I create a visualization and then export it as xlsx.
There is no way (in Qlik Sense) to get a hold on $Table and $Field directly, like:
// doesn't work!
STORE systable INTO 'systable.csv' (txt);
I'm not happy with this workaround, but that is another topic...
F.ex. There are problems like these:
I filtered once, now I cannot unfilter: So I throw the app away and start again...
Yes you couldn't load these fields because there is no table which contains these kind of data - qlik stored the data within data- and symbol-tables, see: Symbol Tables and Bit-Stuffed Pointers and the system-fields contain a certain aggregation from them.
The selections-issue is not quite clear for me - that they are not visible in the selection-panel is normal - the automatic system-fields and also the as system-fields declared fields (per HidePrefix) are per design not displayed. But if put all these fields on the sheet you could deselect them like in all other fields. And even if there is any selection on those fields it won't have an effect on your other selections and data.