Yeah, it seems to be hit-or-miss even with the RTL815X devices; I have one of these and it didn’t work on the AX: https://www.amazon.com/gp/product/B0178HOTOU
… but just so we’re clear, you’re plugging in the USB-C devices via an adaptor into the USB-A port on the AX, right? The USB-C port seems to be power-only (unfortunately).