[WP Smush Pro] Images in Media Library do not load

When Smush Pro is activated, images in the Media Library do not load. Instead, the spinner icon is displayed and it keeps on spinning and spinning. I tried deactivating plugins and themes as outlined in the flowchart: https://premium.wpmudev.org/wp-content/uploads/2015/09/Support-Process-Support-Process.gif
I found that there seems to be some kind of conflict between Smush Pro and WP Offload S3 Lite. But it is not as simple as simply deactivating WP Offload S3 Lite. If I deactivate WP Offload S3 Lite, the Media Library loads "placeholders" for all of the images, but none of the images are actually displayed. If I deactivate WP Smush Pro, all of the images load properly, but of course I no longer have access to the wonderful Smush Pro functionality. For the moment, I have chosen simply to deactivate the Smush Pro plugin, but I would like to be able to re-enable it, if a solution can be found.