Out of nowhere I can no longer use alt+drag to set multiple cursors in a column.

I can use Command + Alt + Drag, but this just appends a column select to whatever cursor is active

Any idea how I can troubleshoot this?

I figured out the problem by uninstalling every single installed package on my system. This turned out to be a bug/conflict with the SublimeCodeIntel package.

Dude. Props for posting your answer! I was having the same problem and killing SublimeCodeIntel fixed it for me as well. Thanks!

It was “Cucumber Step Finder” for me