GeorgesLeYeti: and when you delete task "upload assets" and reladed from provided link? I have no troubles with assets in both Rails 3.2 and 4.0, so you must have sth messed up. Maybe try updating capistrano, but to ver < 3.0
salt_: debug request, check response. If save is performed, then something is happening. Also -= in create.js.erb you forgot ";" at the end of each line. And that's probably your case.