I had an issue using the provided CAP in OPs post. I tried with many different sticks formatted many different ways, using Diskpart and Windows formatting. None of them worked. I took the time to create my own for RIVE (Rampage IV Extreme) by dropping the NVME driver into a freshly downloaded (ASUS Website) rev4901 bios. I will attach it here for anyone that wants to try this one (in case OPs doesn't work for you too).

***EDIT*** Unable to upload because of file size limit. I have uploaded it to the following:
https://mega.nz/file/Pp52yaqL#v5RanKfOG79p9CAY8bvvNCjAY3EKgAkwQ64LOUDYsRM

1. Run command prompt as Administrator
2. Type DISKPART
3. Plug in your USB drive. Note the size of the device (which is likely much smaller than your hard drives). WARNING >> THIS WILL DELETE EVERYTHING ON THE USB DRIVE
4. Type LIST DISK
5. Locate your USB thumb drive. Remember the drive number
6. Make sure you have selected the right device.
7. Type SELECT DISK xxxxxxx               where xxxxxxx is the drive number from step 5
8. Type CLEAN
9. Type CREATE PARTITION PRIMARY
10. Type ASSIGN LETTER=yyyyyyy             where yyyyyyy is a drive letter you aren't currently using
11. Transfer the file attached here to the root of the drive (note I kept it lower case, this worked fine for me)
12. Plug into white USB port on back of motherboard
13. Press and hold the appropriate ROG Connect key until it blinks a few times
14. Wait a while until it is done. The ROG Connect key will slowly blink. If the USB has a light to indicate disk read/write, it will blink too.