Unable to uncheck repository in Software and Updates GUI

Question

I am unable to uncheck repository in Software and Updates GUI. Shouldn't I be able to disable/enable a repository from GUI? I used to be on 16.04. When I click the checkmark nothing happens.

Ubuntu 18.04.

UPDATE:

sudo journactl -xe

gru 08 02:27:03 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Attempting to re-register :1.57/org/ayatana/NotificationItem/multiload; resetting instead
gru 08 02:27:03 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Item :1.57/org/ayatana/NotificationItem/multiload is already registered
gru 08 02:27:03 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Attempting to re-register :1.57/org/ayatana/NotificationItem/multiload; resetting instead
gru 08 02:27:03 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Item :1.57/org/ayatana/NotificationItem/multiload is already registered
gru 08 02:27:03 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Attempting to re-register :1.57/org/ayatana/NotificationItem/multiload; resetting instead
gru 08 02:27:03 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Item :1.57/org/ayatana/NotificationItem/multiload is already registered
gru 08 02:27:03 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Attempting to re-register :1.57/org/ayatana/NotificationItem/multiload; resetting instead
gru 08 02:27:03 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Item :1.57/org/ayatana/NotificationItem/multiload is already registered
gru 08 02:27:04 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Attempting to re-register :1.57/org/ayatana/NotificationItem/multiload; resetting instead
gru 08 02:27:04 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Item :1.57/org/ayatana/NotificationItem/multiload is already registered
gru 08 02:27:04 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Attempting to re-register :1.57/org/ayatana/NotificationItem/multiload; resetting instead
gru 08 02:27:04 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Item :1.57/org/ayatana/NotificationItem/multiload is already registered
gru 08 02:27:04 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Attempting to re-register :1.57/org/ayatana/NotificationItem/multiload; resetting instead
gru 08 02:27:04 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Item :1.57/org/ayatana/NotificationItem/multiload is already registered
gru 08 02:27:04 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Attempting to re-register :1.57/org/ayatana/NotificationItem/multiload; resetting instead
gru 08 02:27:04 Home gnome-shell[5208]: [AppIndicatorSupport-WARN] Item :1.57/org/ayatana/NotificationItem/multiload is already registered

Answer 1

issue this from a terminal

sudo  journalctl -xe    

are you seeing error messages similar to this

Dec 07 20:23:12 zanzbar dbus-daemon[940]: [system] Activating service name='com.ubuntu.SoftwareProperties' requested by ':1.736' (uid=1000 pid=17233 comm="/usr/bin/python3 /usr/bin/software-properties-gtk " label="unconfined") (using servicehelper)
Dec 07 20:23:12 zanzbar dbus-daemon[940]: [system] Successfully activated service 'com.ubuntu.SoftwareProperties'
Dec 07 20:23:21 zanzbar gnome-shell[5892]: pushModal: invocation of begin_modal failed
Dec 07 20:23:21 zanzbar gnome-shell[5892]: polkitAuthenticationAgent: Failed to show modal dialog. Dismissing authentication request for action-id com.ubuntu.softwareproperties.applychanges cookie 2-0f1ecbe09af0c05c92604b792d59300e-2-0c393c45f71b4752192f83f9929be0db
Dec 07 20:23:21 zanzbar software-properties-gtk.desktop[5892]: ERROR:root:Authentication canceled, changes have not been saved
Dec 07 20:23:21 zanzbar polkitd(authority=local)[1333]: Operator of unix-session:2 FAILED to authenticate to gain authorization for action com.ubuntu.softwareproperties.applychanges for system-bus-name::1.736 [/usr/bin/python3 /usr/bin/software-properties-gtk] (owned by unix-user:axo)
Dec 07 20:23:28 zanzbar gnome-shell[5892]: pushModal: invocation of begin_modal failed
Dec 07 20:23:28 zanzbar gnome-shell[5892]: polkitAuthenticationAgent: Failed to show modal dialog. Dismissing authentication request for action-id com.ubuntu.softwareproperties.applychanges cookie 2-0f1ecbe09af0c05c92604b792d59300e-3-3e590c86bc67800a00339ef27868695c
Dec 07 20:23:28 zanzbar polkitd(authority=local)[1333]: Operator of unix-session:2 FAILED to authenticate to gain authorization for action com.ubuntu.softwareproperties.applychanges for system-bus-name::1.736 [/usr/bin/python3 /usr/bin/software-properties-gtk] (owned by unix-user:axo)
Dec 07 20:23:28 zanzbar software-properties-gtk.desktop[5892]: ERROR:root:Authentication canceled, changes have not been saved

if so then just make your changes from terminal

cd /etc/apt
grep -r rabbitmq

then on matching file

sudo vi sssssssssssss

and comment out offending lines