Pro Doorbell Rings Automatically when night mode activates

I installed two separate pro's that go to the same mechanical chime. Both are connected on the 'front' at the chime on a single power pack. They both work perfectly until night mode turns on. As soon as that happens, the chime starts buzzing/humming and the chime automatically 'dings' (without the corresponding 'dong'). I assume this is a power issue, but what can I do to fix it?