Posting a solution for making Sage 10 + Acorn work with WP Engine managed hosting. It looks like there is a future proof solution in the works here however the solution below works as expected.
// functions.php
/*
|--------------------------------------------------------------------------
| Fix Sage 10 to work with WP Engine environments
|--------------------------------------------------------------------------
|
| Override Acorn's view cache path to /tmp/sage-cache if the site
| is running on WP Engine environment.
|
| /tmp/sage-cache/framework/cache path should be present in WP Engine
| for Sage 10 to work. You can ask WP Engine support to create this path on new
| install if not present and make it writable.
|
| This is required for Sage 10 to work on WP Engine as the default
| view cache path is /<YourWordPressInstallRoot>/wp-content/cache/acorn/framework/views
| and with that default path, WP Engine doesn't allow PHP user to execute/write files in
| that directory.
|
| filter ref: https://docs.roots.io/acorn/2.x/directory-structure/#advanced
| is_wpe ref: https://wpengine.com/support/determining-wp-engine-environment/
*/
add_filter('acorn/paths.storage', function ($path) {
if (function_exists('is_wpe') && is_wpe() == 1) {
return '/tmp/sage-cache';
}
return $path;
});