New images tab doesn't work in 4.4.0

[llamafilm]

I upgraded from 4.3 to 4.4, and the new images tab isn't working. (i.e. /dcim/racks/140/image-attachments/). It just shows the filename with no image. I see an error logged from sorl.thumbnail saying "Thumbnail tag failed".

The images work fine at their own page, i.e. /extras/image-attachments/106/

If it matters, my images are stored in S3, I wonder if that's part of the problem? My config looks like this:

STORAGES = {
    "default": {
        "BACKEND": "storages.backends.s3.S3Storage",
        "OPTIONS": {
            'bucket_name': 'my_bucket,
            'region_name': 'us-east-1',
            'location': 'storage'
        }
    },
}

[llamafilm]

I've never used soil-thumbnail, but reading through the docs, it sounds like it stores thumbnails in redis. The Django debug toolbar shows this. Inspecting the redis value, this does not look like valid image data. I'm not sure when/how the thumbnail is supposed to be generated.

127.0.0.1:6379[1]> keys *
1) ":1:sorl-thumbnail||image||8def466cfebdcf1646fa537861fae5a7"
2) ":1:config"
3) ":1:config_version"
127.0.0.1:6379[1]> get ":1:sorl-thumbnail||image||8def466cfebdcf1646fa537861fae5a7"
"\x80\x04\x95=\x00\x00\x00\x00\x00\x00\x00\x8c)sorl.thumbnail.kvstores.cached_db_kvstore\x94\x8c\x0bEMPTY_VALUE\x94\x93\x94."

I tried adding THUMBNAIL_DEBUG = True in configuration.py but that doesn't turn up anything extra.

[llamafilm]

I opened an issue instead. #20212