The Save Show option within Z, is a "quick save" function. If the current show file has already been saved to your USB storage, pressing Save Show will save the show to USB, and will save a new copy of the show file with the next sequential number on the end automatically.
After tapping "Save Show", the Z window is automatically closed.
If the show hasn’t yet been named, ZerOS will ask for a name before saving the show file.
On FLX S, the save icon top left of the internal touchscreen can also be used as a Quick Save option, meaning you don't need to tap the Z/Shift key.