Can't Find Wooden Pressure Plates In House Of Twain Quest

A friend and I have been stuck in the cellar for half an hour and can't find the wooden pressure plates.

 

They should be behind those giant barrels.

If you can't find them, then that means they're likely bugged or something. Don't worry though, because using them is optional to completing the quest.

Spoiler: SPOILERS! - Don't read unless the plates don't work and you want to know what they do

• In the cellar, place items on both wooden pressure plates to access the secret room. Inside there is a sign telling you to throw loot into the beast's eyes.