WiFi UI not working on 4B+?

With the RPi 4B+ with the latest info-beamer hosted I’m not able to get the WiFi UI to work. With the Screen Installation Instructions package I can see that the IP changes to 10.0.0.1/8, icon blinks in the top left of the screen and the LED shows the heartbeat but no WiFi SSID appears on any device I use. What am I missing? If try to join the network manually it fails, saying that it doesn’t exist.

Also: does the UI appear if the network can be associated but the device doesn’t get an IP?

It seems that 2.4GHz is unusable here since it’s full of other networks. Is there any way to set up the WiFi UI on a 5GHz Channel?

It does not. It’s only triggered if the device cannot associate with the configured network. So either the ESSID is is wrong or not available, or the provided password is incorrect. If association was successful the WiFi is assumed to be correct and the WiFi UI is not started.

By the way an undocumented at the moment feature might help to manually trigger the WiFi UI: When the device is still unregistered or within the initial welcome screen, you might use your TV’s remote to open up a menu. Normally WiFi settings cannot be modified, but you can place a file /config/cec_menu.json on the SD card:

{"wifi": true}

There will then be a menu for manually enabling the WiFi UI.

Nope. No option for that unfortunately. It it even possible to have the WiFi 2.4GHz spectrum so crowded that it becomes unusable?