Not sure if this is known about or even needs to be fixed, but I’ll report it. Also don’t know if this is the correct location to post it, feel free to move it somewhere.
Basically I just downloaded Manjaro Cinnamon and installed it under VirtualBox. I then went to install kernel 4.15 before I do a system update, and it shows all the 4.14 kernels as running. (I took the screenshot after installing 4.15.):
So this isn’t blocking anything, I just suspect it isn’t working as intended.