Flex – Row: “Enable Custom child order” without effect

Hi, … again 🙂

I tried to replicate the second example video for Flex options (and some variations of it):

https://greenshiftwp.com/unique-features/#gspb_heading-id-gsbp-54d3650

But the option “Enable Custom child order” does not open the promised block-sorting option (or anything else).

When using box-container as inner blocks, there is a manual Order field in each of this inner containers, but the option “Enable Custom child order” in parent container has also no effect.

What’s the trick?