It's possible you intended for the machine to work this way, just feels weird. The mob slaughter factory will produce meat/pink slime based on damage done to a mob, regardless of weather that mob dies or not. With the default settings, this is most easily tested by spawning a wither for the mob slaughter factory to hit. After a single hit, the wither will remain alive and the mob slaughter factory will have a healthy bit of meat and slime in the internal tanks.

Industrial Foregoing Version: industrialforegoing-1.12.2-1.10.2-178
TeslaCoreLib Version: tesla-core-lib-1.12.2-1.0.14