We run Image proxy to preserve external images 'Image cache lifetime: 0'
I didn't realize that changing the Secret Key would cause a refresh of the proxy cache. It did and I lost 1000's of images that are no longer available externally. Is there any way of recovering short of restoring from a backup?
The secret key isn't involved in determining whether a refresh from the source is needed; it's really for situations involving hot linking. It shouldn't affect whether an image is displayed. Do you have an example URL?
I'm pretty sure all we did was change the key and I didn't notice that we lost all 404'd images until it was pointed out today. If that shouldn't affect this then it's possible that the image proxy was unchecked then rechecked. If that happened, is there any query that can rebuild (assuming we have all the images from an rsync backup)
If the files are present, then they should be used. I suspect that the broken images aren't actually present in the file system.
Are you positive these specific images were working before? To confirm, you'd need a database and a file backup to determine the record in xf_image_proxy that applies and whether the file exists for that ID.