Action: Save for Web; files are getting larger in size!

I am totally confused and have tried everything. I have a folder of images that I want to optimize for the web but everytime I run the Save for Web action, the file sizes increase in size.

This is what I do and here is an example.

I have a photo that is currently 264K in size

Setup a new Action
Resize the photo to 640 width
Click Save for the Web medium 30% quality

File > Automate > Create Droplet. I then drag the folder to the droplet and the action begins. I have also tried

When I run the action, for some reason, the files are increasing significantly in size. For example, the file I had that was 264K, increased to 418KB... However, when I manually opened the image and clicked File > Save for the Web, the file reduced to 87K.

File > Automate > Batch and the file sizes still do not reduce.

Please help!