Steps to reproduce:
Under 'Supervision Functions' click on 'Approval Profiles'
Add an Approval Profile
Click on Edit button for your approval profile
Configure 'Approval Profile Type' as 'Partitioned Approval'
In the 'Name' field insert: Part_1
Change 'Roles which may approve this partition:' to something else than default
Change 'Roles which may view this partition:' to something else than default
Add a Check Box and click on 'Add Field' button
Observe that this results in the configuration to go back to the default.
This will also happen in all partitions if you use 'Add Field' button in one of them.
using 'Add Partition' button results are the same
using 'Remove Field' button results are the same
Workaround is to save each time you configure a field which results the page to go back to the 'Manage Approval Profiles' with 'List of Approval Profiles'