Just ran into this after updating my Linux distro. Issue was that my new bare-bones install didn't have an icon theme, and whatever the fallback is didn't have a grab icon. I could see this by going into the developer console, picking the main leaflet-map div and changing the cursor css proprety to anything but grab (e.g., auto, grabbing, etc.). The default icon theme should be /usr/share/icons/default. Typically this will by a symlink to your actual theme or a directory containing an index.theme file in there that says something like [Icon Theme] Inherits=breeze_cursors and if you check under /usr/share/icons/breeze_cursors you will find a grab file that provides the required icon. You can also have switched from default by manually specifying a broken icon theme. In either case, the solution is just to install a working icon theme.