[seharper]

It's the old "dimmer leakage current" trick.
-
Your doorbell is wired with 2 wires, yes? The circuit is 3 things in a loop: the transformer, the doorbell, and the chime. The R wire comes from transformer and the W wire goes to the chime. The C wire connects chime back to transformer to complete the loop.

So, the doorbell is in series with the chime. Literal series wiring.

So yes, the chime does appear like a resistor to the doorbell.

Now, historically dimmers had the same problem. They took advantage of the fact that an incandescent light won't light with a very low current moving through it. So the dimmers power themselves by leaking a small amount of current through the incandescent bulb.

A traditional solenoid-operated chime will also allow the same thing: a small amount of current can pass through it without activating it. Your camera counts on this to power itself.

However, electronic chimes do not have a solenoid, and have much lower activation currents, and will not allow that kind of "leakage current" to pass through them. A similar problem crops up with LED bulbs and dimmers.

So the camera pops up an error "low voltage" which is technically true, but wildly misleading. The problem is not the source voltage (16V vs 24V), the problem is that the chime is too high-impedance - it does not allow enough current to leak through it... so the effective voltage at the camera's current draw is too low. But you'd have to be an EE to understand that message! LOL!

The solution can actually be a resistor or capacitor in parallel with the chime, to reduce its impedance.