Files in "writable" / Preview via "http" not working, ideas?

iRedds nailed it. If you want to read more these are using called “media servers”. You need a routed controller that can “serve” the files since the writable folder is not web-accessible.

An alternative (but make sure you handle security implications) is to create a symlink in public/ to the files.

You may be interested in this similar project: https://github.com/tattersoftware/codeigniter4-files