Quality Save Image don't work

I’m trying to resize an image previous uploaded from form, work great, except by the quality parameter of the “Save Image” proccesor. Set 70 or 15 is the same size of the new file saved, both with same quality.

image1273×523 30.8 KB

Example:
Uploading a file of 916kb (1800x1800px) resizing to 500x500px, quality 70, final size 136kb.
Uploading a file of 916kb (1800x1800px) resizing to 500x500px, quality 20, final size 136kb.

Everything work great, each image get saved in propper path, only the quality parameter is the problem.

Thanks