Howto to move window to another monitor on the left/right using keyboard shortcut?

In 18.04, the default hotkeys for moving windows to another monitor are Shift + Super + Arrow. Each arrow will correspond to the location of the destination monitor relative to where the focused window is.

Also, are you saying that you do not see a list of hotkeys in Settings > Devices > Keyboard?
I assume you are using gnome-control-center.

What also works is Alt+F7 to grab the window and then move it with the Arrow-keys and release it with Enter.

Thanks to @hiigaran's comment

I see. So the problem is that the gnome-control-center is not honoring your changes to the default hotkeys. What is returned when you do "dconf read /org/gnome/desktop/wm/keybindings/move-to-monitor-left"?

I checked out dconf. It appears my shortcut keys were, as I supposed, in use already for move window to workspace left/right

These settings do not appear in the keyboard settings though as there are no lateral workspaces anymore !!
I guess it is a bug that these actions, although no longer available, still have an assigned shortcut key.

I simply removed the set shortcut keys and everything it working again.