Why are some desktops locked during a dual monitor set up? Sometimes during the dual monitor set up, I can't move a desktop to another monitor. Why??

For example, if I have a dual monitor, I can move desktop 1 to another monitor, but I can't move desktop 2. This happens vice versa. 



I've been living with it for the past 1.5 years but finally got annoyed by it enough to ask it here.
The space that you want to move to another monitor cannot be active.
For instance if you are currently on &quot;Desktop 1&quot; you can move any space to any monitor except for &quot;Desktop 1.&quot;  If you want to move &quot;Desktop 1&quot;, you need to switch to a different space and then move it to the monitor you want.