Currently, there are several instances where data validation errors have a poor UX implementation within Webflow.

The two main examples of this include:

1. Date fields - when manually entering the date with an incorrect format.

2. Multiple-reference fields with unpublished multi-reference items.
   

As an example of the latter, a collection (A) containing multi-reference fields to another collection (B).

If you're adding a new item to Collection A and include a multi-reference item from Collection B, and the multi-reference item isn't published itself (maybe as you've added it on the fly), and then you try to publish the Collection A item, you will get a validation error.

The CMS will then prevent you from saving Collection item A (even as a draft), and you can only exit without saving, completely losing your item data (not ideal on a collection item with lots of fields).

This feels like a bug to me. I've raised this with the Webflow team, and they mentioned:

"that is a known current limitation of the WF CMS data manager when those errors occur that the item data need to be re-entered."

I can see this becoming increasingly problematic as WF users start to create more advanced collections that contain reference fields.