Also working with Alexa/Aruba here. In my case there were some firewall rules, preventing Alexa from talking outbound to the internet. You might look at your AirGroup settings see what's enabled/disabled.
I'm running versin AOS 6.5.4.4 with AP's in tunnel mode. So far so good getting Alexa to talk to Hue and LeMetric. Keep in mind that the traffic isn't necessarily peer-to-peer, it's often making a round trip through your wired network to the controller.