I'm having the similar issue on my 20.04 lts desktop. I'm connecting my second Screen (Samsung Syncmaster SBS 23b300) via standard vga cable.
Whether my primary laptop screen empty or not, When I open control panel, it opens at the second screen regardless it opened or not.(I don't use second screen too much).
As a temporary fix, I am using Super+Shift+Left/Right/Up/Down (It depends on your secondary primary screen orientation. In my case, my laptop screen resides on left and secondary monitor resides on right.) keys to move the control panel to the main display.
I'm having the similar issue on my 20.04 lts desktop. I'm connecting my second Screen (Samsung Syncmaster SBS 23b300) via standard vga cable.
Whether my primary laptop screen empty or not, When I open control panel, it opens at the second screen regardless it opened or not.(I don't use second screen too much).
As a temporary fix, I am using Super+Shift+ Left/Right/ Up/Down (It depends on your secondary primary screen orientation. In my case, my laptop screen resides on left and secondary monitor resides on right.) keys to move the control panel to the main display.