In the options menu the "Include roles" option is responsible for comparing role differencies.
It has a suboption toggle "For role updates, retain members".
In version 5.1.7, irrespective of this suboption toggle setting, role members are deleted if they exist in the target.
(Version is important, since the 5.1.12 is in pre-release phase and 5.1.11 doesn't allow connection to other tenants besides the current user's tenant.)