Welcome to the ROG forum.
Is Armoury Crate fully updated and are there any updates for your ROG Strix Flare II Animate?
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What I will suggest is to use the Armoury Crate uninstall tool from the ASUS Support Center and reinstalling.
Select your operating system then click Show all in blue, it's the third download.
Once uninstalled, install Armoury Crate version 126.96.36.199 and run all the updates.
Does Dark mode work any better after reinstalling Armoury Crate?
If you have any of the usb cables connected to a usb 3.1 port, try connecting the usb cables to usb 2.0 or 3.0 ports and try the update again.
Try resetting the bios to defaults and try the update.
If it still fails, the only other thing I know to do is a fresh windows reinstall, this will fix any problem with Armoury Crate.