With all due respect, your statement that "... the two without numbers do not have charges thus can't be used ..." is false. When you just see the icon, it means you have one charge. As you get additional charges the total number of charges is then displayed.
I have not been able to use one that does not have a number and does not popup, so if you are correct and you have a charge then it is another bug.
I have however witness one with a number disappear from the screen when I used the last and did not have a planet producing one. The same with strategic resource icons no production no icon, production but not a full charge an icon is shown but can not be used.
