Please try the latest 4.1.5 package, see if it is fixed.
If not, we may need to setup a test Rails application to reproduce the bug in our lab. If you have a simple Rails app can be used to reproduce it, please send to us.
Can you do the same file upload with LSWS "DEBUG" logging enabled, with 4.0.20 and 4.1.6, then send the log file to bug@litespeed...
Or, if you prefer, you can send us a temp root password, we can login and trouble shoot for you.