Currently the SUBMIT permission is used to decide whether
- a user can submit a new process
- a user can "Complete Form"
The currently existing UPDATE permission defines if a user can update the workflow process (workflow definition, forms, entry definitions) so it shouldn't be used for checking the ability to complete a form.
Resolution: need to create a new COMPLETE_FORM permission which will be considered only in case of form completion. This permission is available in "Site Content" -> "Kaleo Forms" under "Define Permissions".
Expert forum question: http://in.liferay.com/web/global.engineering/forums/-/message_boards/message/1439813
I could not reproduce the issue on 6.2.x because of a NPE when creating the Kaleo process.