Going to try another clean install of Aura since I tried deleting a bunch of the bundled drivers to save a bit of space.

However, after coming back to my PC today, the Asus mobo device does not appear in iCUE anymore, and attempting to start Aura gave the same 'service currently unavailable' message as before. The Asus mobo device showed up in iCUE after re-enabling plugins.

I ended up doing the following to make it work: Reinstalled Armory Crate, then used the uninstall tool (twice, just to make sure), then installed Aura from the previous link you provided and restarted my PC. I would recommend you contact Asus for support with removing their software from your system.

If all you did was delete files from the program folders and remove a program from the Windows control panel you did not remove all necessary files and services. If you had Armoury Crate installed you need to specifically go to Asus's website, download the uninstaller tool for Armoury Crate, and utilize that to remove the software.

Armory crate uninstall tool download