Created attachment 8944 
Example of color settings not showing any profiles

How to (possibly) reproduce:

Run xfce4-color-settings from a shell. 
On my device, it says "No profiles for the selected device".
Click "+" to add a color profile. Close the current dialog (either by pressing Esc or clicking on X) without doing any changes.
Click on "+" again. The following shows up on stderr:

(xfce4-color-settings:344): GLib-GObject-WARNING **: invalid unclassed pointer in cast to 'XfceHeading'
(xfce4-color-settings:344): GLib-GObject-WARNING **: invalid unclassed pointer in cast to 'GtkWidget'
(xfce4-color-settings:344): Gtk-CRITICAL **: gtk_widget_queue_resize: assertion 'GTK_IS_WIDGET (widget)' failed
(xfce4-color-settings:344): Gtk-CRITICAL **: gtk_container_foreach: assertion 'GTK_IS_CONTAINER (container)' failed

The profile list doesn't show up anymore (see attachment). When the above is done repeatedly, the program sometimes segfaults altogether, or aborts for various reasons such as:

free(): invalid size

or

corrupted size vs. prev_size

or

munmap_chunk(): invalid pointer

or

double free or corruption (out)

or even

free(): invalid pointer

Temporary workaround:
Exit the "Add color profile to monitor" dialog exclusively by clicking on the "Cancel" button