Search for questions with a custom field such as "Multi-Checkboxes" is not checked

Question

In our Jira we have a custom field like "Multi-Checkboxes". How can I look for problems that do not have a checkmark? Flags will not be marked without anything, because this is the only checkbox.

I can find problems with the checkbox set with a simple query:

Colour = "Red"

But nothing that I can think of will find problems where it is not checked. I tried the following:

Colour != "Red"
Colour = ""
Colour is not "Red"
Colour not in ("Red")

Answer 1

I found the answer right after posting:

Colour is EMPTY

Answer 2

If you have several checkboxes and want to find problems when "Red" has not been checked, you can do ... Color - EMPTY OR COLOR! = "Red"