I dug into this further and found there was a bug in our javascript that was detecting if the entered location was a lat long, so it was not creating a point, but was trying to geocode it like an address. I'm not the one who implemented support for using lat long, originally it only supported addresses, I think the guy who implemented it did not test with any negative values for lat long based on the original regex.
This is fixed now in the source code repository and on the demo site.
Thanks,
Joe