After upgrading to Joomla 6 and latest version of SPP and Helix, the offcanvas burger icon has disappeared if it's set to the right side of the header.
If you set it to the left it shows up and the mobile menu works fine.
I deleted my custom.css and cleared cache and the behavior didn't change, then put my custom.css back.
Joomla 6.0
SP PageBuilder 6.1.0
Helix Ultimate 2.2.1
Playing around in inpector, I was able to pull the mobile menu in which had the burger attached adjusting the negative pixels, but it was not operational.