Uploaded images don't show thumbnails in the Media Library (local provider)

Uploaded images don't show thumbnails in the Media Library (local provider): a task in MiMo-V2.6-RL-oss: Agentic RL Environments (MiMo RL release). I'm running a fresh Strapi project with the default upload provider (local, files stored under /uploads). After uploading an image through the Media…