{ “keys”: “ctrl+alt+up”], “command”: “select_lines”, “args”: {“forward”: false} },
{ “keys”: “ctrl+alt+down”], “command”: “select_lines”, “args”: {“forward”: true} },

I added these to Default(Windows).sublime-keymap - these are the same as in Linux and notepad++ in Windows and MS Vicious Studio

{ “keys”: “alt+shift+up”], “command”: “select_lines”, “args”: {“forward”: false} },
{ “keys”: “alt+shift+down”], “command”: “select_lines”, “args”: {“forward”: true} }

Now it works the same for me in Windows and Linux

I really love the power of this editor and the fact it works in Windows and Linux. I personally am not a fan of Apple and I do not like the Mac’s UI much.

I’d say you have a plugin that conflicts with default keymaps. I suggest you to try this bad boy: github.com/skuroda/FindKeyConflicts

Besides ctrl+alt+up and ctr+altl+down have special usage in Windows - they change the aspect of the screen between upside down and right side up. lol
And in Linux Mint they also are used to do other things in X. It would be nice if the default keys were alt+shift+up and alt+shift+down, which is kinda the standard in a lot of windows editors.