Under .\root\mercenary_park\support - Contract "Support Weapons 2": (which I chose Medic) 'Heal 10000 health in a single life'. I just healed 11,774 health in 1 life as Medic (which broke my record for healing in a single life) but there was no progress towards my contract.

Under .\root\mercenary_park\defense - Contract "Defense Classes": (which I chose Engineer) 'Get 3 kills with a single Sentry'. This one was more attainable than the Medic contract yet when I achieved 3+ kills with a single sentry, Level 1, Level 2, Level 3 and Mini Sentry there was no progress towards my contract.

Also under .\root\mercenary_park\defense - Contract "Defensive Weapon 2": (which I chose Engineer) 'Kill with a Sentry'. This one was even more attainable than the previous Engineer contract yet when I achieved a SINGLE kill with my Level 1, 2, 3 or Mini Sentry there was no progress towards my contract.

There are also some "bugs" that allow contract progress for certain kills with weapons like Stock Shotgun where the player can have the Shotgun equipped while another method like "Sentry or Afterburn" finishes off the player and it counts as progress.