Custom fields disappear on page refresh

Overview

Custom fields go missing after form validation or on edit.

Reproduction steps

1. Create a custom group for a component, say Contributions and extend it to a particular financial type.
2. Add custom fields and set them to be required.
3. Create a contribution and select the financial type which the custom field extends. The fields appear appropriately.
4. Proceed to try to save the contribution triggering the formRule. The fields show an error, but they are no longer visible.

Comments: I could replicate this for contribution > financial type based custom fields, but it might be happening on all custom fields which extend a type for the component.