This was a bug that I found out about 2 days ago. There was only 1 mother zombie and 4 survivors, including me. The zombie was tired of being killed and logged off Infected, and the game kept going until the timer ran out.
Instead of keeping it this way, add something that would fix this issue. Say all infected leave. In 10 seconds, the game will pick a brand new mother zombie in order to keep the game going.
