Destructable Panels at Guardian Sites

[Al-Lunar]

I don't know if I'm missing something obvious, but I'm trying to gather resources at a Guardian site. I have done the blueprint fragment process, and now I'm trying to get additional materials from behind destructible panels... except I can't target them at all, it seems. I have approached every structure at the site, but there's no indication of these panels-- not on my targets panel, and not on-screen either.

What am I missing?

EDIT:
Thank you all for the lightening-fast responses! Came back at night and, ironically, it was clear as day! Now I know exactly what I'm doing for these. o7

 

[Retropolitan]

Your scanner will only show them at a pretty short range - definitely watch for white indicators that appear and disappear down there. Also, you can often spot these in the distance because of their slight blue glow.

 

[Borko]

Gotta get close and flip to the turret. You’ll see the grey diamond come up then you can target it and crack it open for goodies.

 

[Sublime]

You don’t need to actually target it. Once you learn to recognize them you can just shoot them from afar. They have a blue glow and are easier to spot at night.

 

[Para Handy]

Easier to detect on your scanner but easier to target and shoot in turret mode. You will get the hang of it and soon will remember the locations (well most of them ).