On Facebook, when you hover over your "like" button with the mouse and the text popup says "No one currently likes this." Even tho you have at least 1 "like" Showing up.
Mainly cause by who ever liked your status or comment blocked you, or you may have blocked them.
You: Hey that's weird! Someone like'd my comment. But when I cover over it, it says "No one Currently likes this"
Facebook Friend: I see it, it says "First Name Last Name likes this!"
You: Than that person might've blocked me afterwards. So it's an Invisible "Like". lol