AX8 (RAX75 Costco version) not operating at HT160?

I'm having a hard time getting a solid answer on this issue. I opened a support ticket and they were not useful.

I have the RAX75 from Costco, Firmware Version V1.0.1.70_1.0.30

Does this RAX75 support HT160 or not? The box claims it does. The router config page also sort of does: I can select 4330 Mbps (AX off) or 4800 Mbps (AX on) modes.

However, when I use a wifi analyzer, it does NOT show the 160 MHz channel width, only 80 MHz (though it indicates that the router would support it).

I have a Killer 1550i, which has 160 MHz support. Attached are screen shots of the Killer Wireless wifi analyzer with the router at different settings, either with 4800 Mbps or 2400 Mbps mode enabled. As you can see, the wifi analyzer shows the same channel widths for both settings (80 MHz)

iperf3 bandwidth between two gigabit wired connections was over 600 Mbps

iperf3 bandwidth between killer wireless and gigabit wired was only 420 Mbps, when sitting less than 2 feet from the router (4800 Mbps mode)

iperf3 bandwidth between killer wireless and gigabit wired was around 380 Mbps, when sitting less than 2 feet from the router (2400 Mbps mode)

So the 4800 Mbps mode is definitely a bit faster, but not substantially. Am I just expecting too much out of this router? Is the wifi analyzer just wrong in how it's displaying channel width? Is there any other way I can ensure that it's using HT160? 

This is NOT a DFS issue, as I can leave the router on a DFS channel indefinitely and it doesn't get dropped or changed.

Any thoughts or help would be appreciated, thanks!