Hi,
I was able to replicate this bug. I am going to look into this week.
As a work around, looking at code seem a simple issue and I can tell right away that you you can pick 0 and then you will have all channels to pick from 😉
However after testing, the card does not come back so there are more issues on both wifi-manager and start-wifi scripts. Basically the script cannot distinguish between 2.4n and 5n.
I need to read more about how command line works on wifi card.