Hi there,
Glad your using WP-Forge as well as WP-Starter.
You stated the following:
However, when I turn off the child theme and use only WP-Forge the menu works as displayed.
So this tells me that there is something wrong in your child theme. That’s all I can gather at the moment.
I tested both the latest version of WP-Forge and WP-Starter, both with the off-canvas menu set as main menu as well as with top-bar set as main menu and off-canvas set as mobile menu.
So I cannot say why it is doing that just by a screen shot. If you would like to send me the login info you can do so by contacting me via my sites contact page https://themeawesome.com/contact/
Glad we got it worked out via email 😉