Cannot update RT-AC68U firmware

My RT-AC68U router is currently running firmware version 374_583.

I want to update it to version 378_4585.

I've tried to do so three times.

Each time, I click "Upload", the progress bar "finishes", and I receive a message that the update has completed.

However, the firmware version never changes.

I've tried doing a reboot from the browser-based UI.

I've tried recycling power on the router.

Any suggestions?


Thanks