Forgive me, I am not sure I understand completely what you are saying, does this seem right to you ?
Have a circuit includes about 7 lights.
They work , Stop working, Start working again
When lights stopped working, no breaker was tripped.
Went to each outlet and switch and none of the wires or connections looked bad
Tested with a tester that uses a light bulb - it would light up when touching the Hot wire and the electrical box that holds the light or switch.
Tested with multi-meter and got 120 Volts from Hot wire to electrical box.
Do light bulbs use 120 Volts where you are, or 240 Volts ?
If your breaker stays on, and if your breaker is good, you are not getting a short between power and ground.
But you could have a bad neutral wire, and the lights turn on by using the Hot wire and ground. This would be an open neutral wire, like you asked.
I think the lights work some days, and not other days because of some switches being on and some being off. I think you test the lights using some switch, but not always the same one. This makes it hard to find out where the problem is.
We need to work on only 1 thing at a time, all other things must be the same.
The next thing for you to tell us, is how many switches, and how many lights go to each one.
Something like this:
8 total switches
10 total lights
for outside lights - 1 switch and works 2 lights
for hall lights - 2 switches work 3 lights
for closet lights -
1st closet - 1 switch and 1 light
2nd closet - 1 switch and 1 light
recessed light -
1st lights - 1 switch and 1 light
2nd lights - 2 switches and 2 lights
I hope I make sense - problem is small , but makes many things not work
we will find it - the lights will not win
Ask questions, I will do my best to help