Can't weigh down some pressure plates

In a temple, trying to weigh down a pressure plate at the bottom of the screen is impossible, and you can't rotate the camera to get around this.

In the image I'm trying to weigh down a stone plate with a 1 gram raddish (normal behaviour) and the option to 'weigh down' doesn't appear, because it thinks you're trying to put a raddish down on the south wall. For the record, I can weigh down all other pressure plates