I discussed this with Alex Balashov off-line, and he answered my questions:

  1. A flag of 3, I don’t understand.  I read the documentation, and there is a 1,2,4,8,etc…  So, I’m guessing that a flag of 3, means 1+2?

Yes, apparently this is a bit array: https://en.wikipedia.org/wiki/Bit_array and a value of 3 = 1+2.

  1. If #1 is true, then "the "received" test is used: address in the “Via” header is compared against source IP address of signaling”
    1. I don’t understand this test, as I’m pretty sure that the 200OK that’s getting re-written is properly constructed.  I guess I’m trying to understand when one would want to use this test?

Although we weren’t able to come up with an example for this test, it does not seem to apply to my environment.  Updating the flag to 1 solves my issue.