I'm such an idiot. :S
When I unscrewed the existing brackets the plate dropped down and I didn't realize it was there. That will teach me not to try and install a CPU onto a motherboard that's already in place. Thanks for the tip.
I'm installing a Ryzen 5 1600 which came with a wraith spire fan. The motherboard has two brackets to clip a cooler onto but this fan requires me to remove them and screw them into the board. Unfortunately once the brackets are gone there are just holes in the board with nowhere to screw the fan...