Hi there!
Thanks for contacting us.
The menu Items are there but in white color so not visible. If you change the color of the background or the items then they will be visible.
I am giving you custom code for changing the offcanvas menu background color, please put the code in your custom CSS:
.offcanvas-menu{
background: #000000;
}
Note: Path towards custom CSS(Joomla 4): System>Site Templates Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.
https://prnt.sc/5mBuSRh907N3
https://prnt.sc/ooiq-lkMEXr_
https://prnt.sc/nunlX-f5AhK1
Best Regards