It often does, but not always.
It is. Above that, the PLL loses lock, which means the data, although still available, is almost certainly meaningless.
The latest version is 1.9 I don’t understand Github, so I release the latest on the forum here Update to 3-Phase PLL sketch - #21 by Robert.Wall, Github tends to lag behind.
You should never need to put a c.t. on the neutral of a 3-phase supply. If you know your 3-phase theory, the neutral current ideally is zero, in reality it is the imbalance current - the vector sum of the three line currents. If you read the documentation that’s in the zip file when you download from here, you’ll see where you can use CT4.