Cannot flash file from USB

Not sure why there isn’t a simple guide for this product or at least one that’s easy to find.

Anyway, source USB is in slot 1. Target sd card is in slot 2. Source is 64GB drive with a 30GB img file. Target is a 512GB card.

When I go

Deselect target drive
Hit select 1
Hit flash from file
I just get a blank device page

What am i doing wrong?