plugin is breaking image uploads

For some reason the plugin has stopped working. I switched from Smush a few weeks ago, and it was working fine until today.

When I upload images, the thumbnail is not generated and it will eventually give an http error. there may be other image sizes not generated but I cannot see those.
If I disable ewww plugin then everything works as normal.
If I then re-enabled ewww and try to optimize an image it just spins and spins for a long time

Yes wordpress and all my plugins are up to date.