Kyle Reicks

This sounds like the behavior I designed. The `sizes` attribute is used to choose the image size for output. The default `sizes` for your medium image should be `(max-width: 720px)...

Very sorry to hear that the plugin isn't working as expected. If this is a server timeout error (usually a 504, but sometimes it masquerades as the more general 500)...

Sorry for letting this slip by me. Which file is listed in the error? If your are using ACF for images, I wonder if you might have the return value...