Can't update Samsung S24A600U monitors

I have 2x Samsung S24A600U monitors, both running firmware v1010.0

There is a newer firmware on the Samsung website, v1016.0, that I'm hoping might help with a minor USB-C PD issue (laptop doesn't charge if connected to the monitor at boot time, only if connected afterwards).

I've downloaded the firmware file from https://www.samsung.com/uk/support/model/LS24A600UCUXXU/ and have then extracted the single file from there and placed it in the root directory of a 4GB USB stick formatted to FAT32.

As per the instructions, I then plug this in to the Service USB port on the monitor and go into software update on the monitor menu, but after a minute or so it comes back and says that it cannot find any update files.

The file name on the USB is M-A6U00SGZA-1016.0[7DAB].bin and the monitor says it is looking for an M-A6U00SGZA-* file, so everything should be ok.

Any idea what's wrong?

ta