I replaced the original Hue Bridge with the new square shaped HomeKit compatible Bridge.
Unfortunately, no matter what I did, I could not connect my original Hue lights to that bridge. More recent purchased lights connected no problem. But the 3 original A style lights would not. And I tried everything. Reseting, uninstalling, auto find, manual find, changing channel, etc... even holding the light and bridge so they were touching. No luck.
I was not going to call the Hue 800 support number, as they would just have me redo everything I had already done. Then I found this tweet.
After downloading and executing, a program ran that walked me through each of the 3 lights and connected them. Easy peasy. Not sure why it is so hard to find this and so easy to use.