I don’t know if this is by default on mac OS, but when I select a variable and I want to search for it in my project folder, that variable isn’t copied to the ‘Find:’ field. On my windows machine that works fine.
I’m using the default shift command f key combination.
Also the build version of Sublime is 3126.
Yes, this is the default on OSX. You can override it in your user Preferences.
// If true, the selected text will be copied into the find panel when it's
// shown.
// On OS X, this value is overridden in the platform specific settings, so
// you'll need to place this line in your user settings to override it.
"find_selected_text": true,