Steps to reproduce:
create a work group with user Peter who is NOT a group manager
create a patient record and set the group to be the owner of the record
login as Peter
try to make any permission related change (add/remove collaborator; make record public, etc)
PROBLEM: unable to save any change; the only way to close the permission dialog is to cancel the changes
Observed in the family record form as well.
This problem does not exist in version 1.3.7.
In 1.4RC1 I was able to modify permissions via REST API.