Every time I tried to enable the device auto mount on my second hard drive, it never worked. I always had to manually mount it through KDE’s GUI whenever I wanted to access it’s content.
I later researched and found out that I could edit the /etc/fstab file with my second hard drive’s UUID, which caused it to always mount on startup as I wanted.
So my question is, why doesn’t KDE auto mount also replicate this process of editing the /etc/fstab?
The KDE auto mount never worked on plasma 6, I believe it’s something related to wayland (even though I don’t understand how they could be related).
What’s used under the hood for this is udisks, the same thing used by other file managers to achieve mounting capabilities. It allows you to mount devices without needing to mess with something cryptic and archaic like fstab and doesn’t require root.
You can always keep using fstab of course since it works, but in that case you probably also want to use fstab systemd integration.
Please report your issues on https://bugs.kde.org so they can actually get fixed!