"Does Chanalyzer 5 + Wi-Spy DBx Support 802.11ax?"
Yes!
Spectrum Analysis 802.11ax Support
Wi-Spy DBx is a spectrum analyzer. It hears all raw radio frequency activity in the 2.4 and 5 GHz bands, including 802.11ax activity.
Spectrum activity example (80 MHz wide)
WiFi Scanning 802.11ax Support
Using inSSIDer WiFi scanning technology, Chanalyzer 5 also overlays WiFi scanning data on the spectrum analysis data provided by Wi-Spy. This WiFi data is provided by your wireless adapter. Any dual-band adapter will soon display 802.11ax channel widths and data rates. For more details, check out the WiFi Adapter Buyer's Guide.