Update from GitHub
If there is a bug in EWWW IO, the fixes will land on GitHub before they ever make it to a release on wordpress.org. So if you want to get the latest fixes, you can download it from GitHub and install it. But that might be an entirely new process to some, so let's break it down. *Note that this same process applies to any of our plugins: Easy Image Optimizer, S3 Image Optimizer, etc.
Note: GitHub has this annoying habit of adding "-master" to the folder structure which causes some problems for WordPress. So we repackage the dev version of EWWW Image Optimizer on our API servers.
Download latest EWWW Image Optimizer
Once downloaded, go to Plugins->Add New and then click the Upload Plugin button at the top of the page.
Then, click on Choose File, and find the zip file that you just downloaded. Click Install Now to upload the ZIP file and unpack it on your site.
WordPress will detect that you already have the plugin installed and ask you what to do about it.
Go ahead and hit the Replace button, and when that completes, that's it!