Autoprefixer doesn't add vendor prefixes - gulp

Question

Here is the task :
gulp.task('process-css', function(){
return gulp.src('./app/css/scss/main.scss')
.pipe(sass().on('error', sass.logError))
.pipe(postcss([postcssMixins, postcssCalc, postcssSimpleVars, postcssColor, postcssExtend, postcssNesting, autoprefixer]))
.on('error', function(errorHandler){
console.log(errorHandler.toString());
this.emit('end');
})
.pipe(concatCSS('style.css'))
.pipe(gulp.dest('./app/css/'));
});
I'm using the standard autoprefixer plugin (not gulp-autoprefixer, which basically did the same thing on the last task-runner I was using), but it only adds the -webkit- prefix. I tried it with properties like clip-path and display: flex, but it doesn't add the vendor prefixes. I tried changing the line to
.pipe(postcss([
postcssMixins, postcssCalc, postcssSimpleVars,
postcssColor, postcssExtend, postcssNesting,
autoprefixer([{browsers: '> 0%'}]))
but that didn't work either, what is wrong with it?
-- Fixed --
I think some of the other plugins is using autoprefixer too and it was messing with my configs. The way I fixed it was to add this at the bottom of my package.json file
"browserslist": [
"> 0%",
"last 2 versions"
]
Add it with a comma after the last curly brace for your devDependencies

Answer 1

Flex is very well supported so probably you don't need it anymore (autoprefixer don't add prefixes to the property by default anymore for a while — check can I use). But if you really need it you can do the steps:
Let's say you have css folder and dist folder for yours styles in your working directory.
create .browserslistrc file at the root of the working directory and put last 4 versions in it.
run postcss css/styles.css -u autoprefixer -o dist/styles.css in your terminal