Haru, if you're sure that both your iPads are on the same wireless network, and ShutterSnitch is running, there are two things that will make the other device NOT show up in the Bonjour section of the Locations dialog:
1. If the other ShutterSnitch is in the collection overview.
2. If the other ShutterSnitch is inside the selection mode (the mode where you can pick images to transfer to somewhere else).
So make sure you're simply inside a collection on the device that should receive the photos.
Here's a video of how it should work.
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