Without seeing the exact configuration you implemented, nor debug log, it is difficult to understand what can be wrong.

I suggest you:

compile nginx with the --with-debug option and activate debug log with the error_log directive. check the debug log for the /progress request and look the order of the tested locations.

It is well possible you are using try_files and your /progress location doesn't trigger because it is located after your catch all location. You can try to put the /progress location at the top of your server {} directive