Not a problem, I understand how frustrating this can be. Expectation is that pagination works and when it stops and goes into a loop like this, would be very hard to detect that and could cause integrations to go crazy.
We do have good news. On further investigation from the team, our v2 API is paginating correctly (pagination next links for v2 look surprisingly similar due to hashing, was a user error thinking they were the same when off by one character). We are looking into the way the v1 API hashes pagination values to see why we're getting stuck in a loop now. Hopefully will have another update soon.
Dave Berard Senior Product Manager, Constant Contact