Ineligible Players?

How is it that an opposing player that is classified "Ineligible" for war, abe to attack in the current war? This has happened three times in our war experience. Maybe I don't understand the meaning of the timer on players profiles that delet their Lv from infront of their Name's. What does it mean when it says " Eligible for War in 12 Hours"???

Players have war cool downs and cannot participate in more than one war at a time. If they are currently in a war it says on their profile the time remaining until they are eligible to enter another war. This is why new players joining a clan cannot always join a war because they left a clan and war behind that they are still engaged in.

Then how can they attack in the current war if they are not eligible?

The timer refers to new wars. They're not eligible to engage in a new war as they are currently in one (the one with your clan).