I'm on OMV 6. I installed the kernel and Gparted plugins no problem. In 'System/Kernel' I selected Gparted live and then used the icon to select 'Reboot to Gparted live once'. I then attached a keyboard/screen to my OMV server and rebooted. The boot screen shows various Debian, Debian recovery, memory test and finally the Gparted boot option (bottom of list). I use the arrow to scroll down to Gparted and hit return to boot into Gparted. But, as it boots I see an 'insufficient memory' mesage and a 'must load kernel first message' . Gparted doesnt start. I reboot and select the top of the boot options list (Debian 11.....). It then boots back into OMV fine. EXCEPT (I think this may be unique to my setup) I cannot load the OMV console GUI in my browser, it just sits there forever saying 'Loading...'. This happens the same in both Chrome and Edge. I eventually tracked this down to cached images in both Edge and Chrome. Clearing the image cache cured the problem. I only added the cahce issue to this post in case it helps others.
My reason for posting is to try and get a solution to the Gparted problem