Check the following settings on Settings Manager - Power Manager - laptop lid
and verify the true behavior vs the expected one:

On battery: lock, Plugged In: lock
Expected behavior: lock (on batt), lock (on AC)
True behavior:        lock (on batt), lock (on AC) YES, YES

On battery: suspend, Plugged In: lock
Expected behavior: suspend (on batt), lock (on AC)
True behavior:        suspend (on batt), suspend (on AC) YES, NO

On battery: lock, Plugged In: suspend
Expected behavior: lock (on batt), suspend (on AC)
True behavior:        suspend (on batt), suspend (on AC) NO, YES


On battery: suspend, Plugged In: suspend
Expected behavior: suspend (on batt), suspend (on AC)
True behavior:        suspend (on batt), suspend (on AC) YES, YES

As you can see, the suspend action is an OR operator and Lock action is an AND operator.