According to Bruce Schneier's blog, hackers captured a Flock automatic license plate reader (ALPR) camera and reverse-engineered it. The joint analysis of the recovered data focused on the software running on the device.
While much of the most sensitive storage remained encrypted and inaccessible, the recovered data still provided a look at the software. The post does not specify what the software analysis revealed, only that it was possible.
This suggests that even when encryption holds, other components of a device may be exposed to physical attackers. The source is a single blog post, so no independent verification or additional details are available.