Hello,
I have tried first solution in (1.), but it seem not working so I also try deactivate single product builder and use elementor’s theme builder the form add to cart still not have quantity button [ – ] , [ + ]
Here is my ref that I have to do (https://www.imagevenue.com/ME15NGKN)
Please help take a look in my dashboard, info is in private content.
Regards.