So I had an older Elgato TB2 hub lying around and wanted to connect it to my 2020 Intel high-end 13" MBP. I found an Apple TB3-TB2 adapter in a drawer and hooked it up.
I started by using the MBP’s port closest to the edge (farthest from the trackpad) on the left side. Nothing. Disconnected hub, reconnected, still nothing. Power cycled the hub. Still nothing. Not even a USB KB connected to the hub worked. Hub works just fine on an older MBP so I know it’s not the TB cable. Anyway, Sys Profiler showed nothing attached. So then I switched to using the other port, the one closest to the trackpad and presto everything worked as you’d expect.
Due to the way peripherals are connected to the hub (and the silly short cable) I only tried the ports on the left side of the MBP. So my question is, is there some kind of known limitation of the TB3 ports on this MBP where only some work with hubs, or is this an indication one of my TB3 ports is wonky? Admittedly, I otherwise usually only use that port for charging so I have no idea if USB peripherals work on it. Hardware diagnostics reports nothing though for whatever that’s worth.