Update the RPi5 to https://chewitt.libreelec.tv/testing/LibreE…h64-11.80.0.tar with the ASIX adapter connected and share the log URL from "journalctl | paste" please. I've made the drivers built-in to the kernel (=y) instead of using loadable modules (=m). That's not necessarily the right fix, but takes udev (which I think is the issue) out of the equation temporarily.
Looks like the ASIX interface still didn't come up. There is no eth1 interface available. Here's the journalctl log:
https://paste.libreelec.tv/holy-heron.log
Let me know if there's anything else I can do to help diagnose this.