Can’t communicate between wireless bands on a satellite

Here's a practical example. The mac I'm typing on can't ping a tuya lightbulb joined to the same satellite on 2.4ghz. Yet the iphone next to me (joined to the same satellite on 2.4ghz) can ping it fine. The mac is on 5Ghz and can ping anything else on 5Ghz on the same satellite quite happily. It can also ping things on 2.4Ghz hosted on the router or another satellite just fine. I had a raspberry Pi join the 5Ghz on a satellite running some home automation - and of course everything failed as all the iot devices on the same satellite are on 2.4Ghz! (cleared mac arp cache of course, makes no difference). 

House - 1500 sqft. Devices are less than 30 feet away from each other. Its an old brick-built house so not like foil from insulation is in the way, and Router connection to satellite says 'good'. 

This isn't an issue on the router - pinging between bands works fine. So seems like a satellite firmware bug to me - i.e. looping back to a device on the same satellite but on a different band doesn't work, but I'm a sample-size of 1. Anyone else able to try it? Should be dead easy to prove.