Well, what did your Capture Counter say at the end of the game? (Where it shows your Results and Exp. Points)

I believe Obitual and I have had this conversation before as we've both had situations like this happen to us. When the survivor leaves before being officially killed (all of their health is gone or all of them are in pods so they all die simultaneously) it is not counted as a capture because while yes, you did put them in a pod, they never actually died.

This is also reflected in the end screen under "Survivors Captured" as MrWindy does not count rage quitters as captures unless they died before they left.