Has anyone noticed that the Spark's weird latch-lock mechanism is a big part of the problem? The "locking" mechanism on the car's side consists of a large portion that pivots/rotates down, and is pressed into this rotated state by the tip of the charging handle. Then, only after the top portion is pivoted by the latch tip, there is a locking bar that slides in from the left, back-holding the pivot/rotate portion in position. This is the only EV I've seen that does it in this strange way.
It's prone to fail on certain latch tip designs not because they're too big, but because they're too small. The latch tip doesn't pivot/rotate that bit enough, thus the locking bar collides with it instead of holding it in position. Because it can't slide into locking position, locking fails, and charging fails. If you want to test this, just make sure that "flippy" metal part of the charge port is indeed "flipped" (using a poking stick of your choosing) while it's trying to lock - if it even gets so far as to lock, that is. If it gets to a point of trying to lock, you're in good shape (it's communicating!).
