It doesn't sound as if the nest is very secure, so it may have been abandoned for that reason. Activity tolerance varies a lot--I have seen many a nest in busy plant nurseries, or next to the sidewalk of active businesses. Some mother hummers are calm, and others dive at everyone that walks by.

Females that have had a successful nest season will often return to the same general, or even the exact, location the following year. This might be the same female that nested on your lights last year. If so, and if the two locations are not very different activity-wise, perhaps she is already comfortable with the amount of activity in that area.

If eggs were not yet laid, it is possible she will build another nest nearby. It isn't unusual for the bird to leave and return for stretches at a time during construction and egg laying.