only superuser and staff can save form entry

[jamesmc]

Describe the bug
Form submissions will only save if the logged in user is superuser or staff.

The behaviour is inconsistent: sometimes a form entry will save from a logged in user who is neither superuser nor staff, but this happens rarely and I cannot work out what conditions have to be met for this to occur.

Expected behavior
All logged in users should be able to submit forms and have the data saved as a formentry

Desktop (please complete the following information):

• OS: djangocms running in docker container django-cms-quickstart
• Browser: Firefox on macos.