Cannot remove role

I have many user roles created and we are using the Ultimate Member plugin.
I am using your plugin to assign multiple roles for the user accounts.
The problem is that I want to remove one of the roles from some users, but when I uncheck those user roles and save the user account, the user role is not removed as it should be.

I see that another user reported this issue on the www.remarpro.com plugin listing about 3 months ago and never received a reply.
Any assistance would be appreciated.