There is an instance where using the comb on a grid with multiple types of poles, that there will be a complete disconnect between two sections.
Repo Setup:
Place two Big Poles max distance horizontally, a Substation directly next to the left Big Pole, a Medium Pole max distance from the Substation to it's right.
The bottoms of the poles must align horizontally
(rough visual spacing guide)
BBSS________________BB
BBSS____M___________BB
Moving the Medium Pole up one grid will prevent the disconnect bug from being tested.
It looks like there is a pull request from 5 days ago (day before the latest release) that might fix this:
https://github.com/shanemadden/factorio-power-grid-comb/pull/13