So, the Resizable Grid not working anymore?

in Google Chrome 79.0.3945.130 _win10(64) + F7 5.4.0
looks not working in my pc(NOT Resizable)

however, in cellphone’s Browser when I ‘touch’ it works again.

It works for me (Chrome 79.0.3945.130 on Win10 PC Desktop)

However, it stops working for me when I switch Chrome into responsive design mode for iPhone.

Potentially this is on purpose - On a mobile device, there is no ‘hover’ state for a cursor, so you wouldn’t be able to offer a ‘resize’ cursor. Maybe it’s just a feature best suited to desktop development.