Concurrent writes to the same folder on an S3 bucket using the JavaScript SDK v2

Hello, I'm having some issues while using the JavaScript SDK (S3.ManagedUpload) to dynamically upload images to an S3 Bucket.

Right now I have a bucket that contains a folder for every resource, and the folder is identified by the resource's ID (which is unique). Everything works perfectly when trying to upload one image at a time, however when trying to concurrently upload multiple files to the same folder (eg: :resourceId/*), some images get deleted after a short amount of time (even though I get no errors at all during the upload). I tried firing a GetObject right after uploading them and they indeed exist, however if I ping them again after a short delay, some return a "Key Not Found" error

Any help would be appreciated, thanks.