Puddling and feeding butterflies are my favourite moments for butterfly photography.
Since you mentioned it, I just realised that I’ve not witnessed any butterfly group getting predated upon during their vulnerable moment.
My guess is that puddle sites are not within easy reach of lepidoptera predators like birds and lizards.
The last puddle site I photographed butterflies was a small patch in a rain forest next to a pool. Here >> https://www.inaturalist.org/observations/82056591
Birds or lizards may be wary of venturing into such unfamiliar locations for food for fear of being predated upon themselves. The forest is a wild place. The hunter soon becomes hunted most times. Again, forest birds spend most time in the canopy, hardly exploring the floor for food.
Other puddling sites are river or stream beds which may be rocky, sandy or muddy, and may pose a huge risk for predators on the prowl. Think of a lizard or bird getting stuck in a mire :)
I however witness more vulnerability of butterflies at night while they roost, and predators as geckos, frogs are on active hunt for them.
I hope this helps. Meanwhile, I’ll be on lookout for strong records for this.