systemdlete:

Supply the following if possible:

• Device problem occurs on
  VM x86_64 router upgraded from 19.07.8. Router has 512M memory. VM was flashed from 19.07.8 with the squashfs image.
• Software versions of OpenWrt/LEDE release, packages, etc.
  This occurs on 21.02.0; the MAC override feature worked at least nominally in earlier versions; the interface would correctly reflect the overridden MAC address.
• Steps to reproduce
  Network->Interfaces->Devices->Configure set the override MAC field to desired MAC address. Save, reboot (just to be 100% certain). MAC address remains as before the change.
  Please note that the new MAC address is reflected in the system. "uci show network" does indeed show the change in a new section network.@device[0].macaddr, so LuCI seems to be making a change. It is just that the system proper seems to ignore the change.