ASUS: "Winflash does not support this BIOS update."

Question

I'm trying to flash a new BIOS/UEFI firmware on my ASUS UX330UA. It currently has firmware version 300.

Easy Flash 3 (inside the current firmware)

Using EZ Flash 3 (booting to setup), I can browse the folders on my USB key, but cannot see any files. Why can I only see directories, but not files?

Windows

I have already removed and re-installed the latest ATK, and also installed the latest version of Winflash from the Driver and Tools tab under Support.

When I run Winflash, I get the following error:

How can I flash the most up-to-date BIOS/UEFI firmware?

Solution

It appears certain versions of EZ Flash will not display any filenames unless their extension is .CAP or .ROM.

The file that I downloaded was named:

UX330UAK-AS.302

I made two copies of this file, namely:

UX330UAK-AS302.ROM
UX330UAK-AS302.CAP

Both of these copied files with "correct" extensions were then shown in EZ Flash 3, and I could successfully update the firmware.

Interestingly, it seems this is an unlisted bug - the version of EZ Flash 3 in the new firmware that I flashed showed all files, regardless of extension.

Regarding updating via Windows, I can only assume that Winflash needs to be updated to support the UX330, which is newer than the filestamps on the latest version at the time of writing.