HI @twistysnacks
aah, I think I understand the issue now.
When saving a value, the value MUST be in the correct format for saving. This means, images / files muct be saved as an attachment ID.
If you are trying o save a URL as the value, ACF will fail to save the data entirely.
You will need to change the return type of your file field to return the ID, or Object. These can be saved, not the URL
