Alright folks, I think I've found a possible solution to this problem.
On my particular setup, I had everything configured correctly according to Ken:
1.
Blue Iris General Web options were correct, showed my correct WAN IP, and the port Blue Iris was using was opened via my firewall
2. Blue Iris iOS app was configured with my correct WAN IP and port
But pictures for push notifications still were not coming through, in spite of Blue Iris being updated on the computer and iOS devices.
However, earlier this week I updated my iPad from iOS 10.2 to iOS 11.0.2. I had stayed on iOS 10.2 on both my iPad and iPhone to stay jailbroken on those devices. I uninstalled and reinstalled Blue Iris on both iOS, then I added both devices to receive push notifications in Blue Iris General settings. Then I hit test.
Presto -> the iPhone still on iOS 10.2 did not receive a picture with the push notification. The iPad on iOS 11.0.2 did receive the picture.
I see when Blue Iris 4.5.8.5 was released iOS 10.3.2 was the most current version. I think it's entirely possible that Ken may have used software calls that only work in iOS 10.3.2+, and those calls don't work or don't exist in < iOS 10.3.2.
So here's a question to anyone that doesn't have pictures for push notifications working:
What version of iOS are you running on your device?