Docker container can't put macvlan wifi adapter into AP mode

I’ve created a Raspbian-based container for flashing firmware (wirelessly) to smarthome devices. The software to do so works fine on a Raspberry Pi so I installed all the software, and all prereq’s in this container (which is running on a Raspberry Pi). I’m using the same USB wifi adapter that worked properly on the physical RasPi, configured as macvlan (with the wifi adapter selected as the parent network card). The wifi adapter IS working - I can successfully ping google - but when the start_flash script does its magic, there’s supposed to be an SSID (vtrust-flash) that I connect to with another device. There is no such SSID listed for me to connect to. I must be missing something in the macvlan configuration but I don’t know what. The whole procedure (which, again, works fine on a physical RasPi) is located here:
There’s an associated video procedure here:

I know this is a pretty esoteric application/question but it sure would be great if I could get it to work so that I didn’t have to dedicate a RasPi to this and could fire it up any time I wanted to flash some devices.

Thanks for your time and consideration!

Hello there, I’m having the exact same issue (macvlan the wlan0 interface and not being able to put it in AP mode), did you solve it?