By clicking on the delete button on the fieldset sidebar, the fieldset can't be deleted.
Steps to Reproduce
- Go to Content & Data > Web Content > Structures
- Add a Structure and select to create a fieldset.
- Inset a text and numeric field and pt it on the structure.
- Click on the save button and go back to the Strucutre.
- Delete the fieldset on the Structure.
- Go to the sidebar and delete the fieldset you had created.
The fieldset is deleted properly.
The fieldset can't be deleted.