The sample programs run fine, and I can compile and run your WPF demo just fine. So obviously I'm doing something wrong, but I have no idea what.
In my output directory (at the root level) I have the 64-bit astra.dll, astra_core.dll, astra_core_api.dll, and AstraDotNet.dll, along with my main executable. My build target is x86_64, so it's not an architecture mismatch error.
Here's the output that gets logged to the console:
2018-01-03 10:12:41,094 WARN [context] Hold on to yer butts
2018-01-03 10:12:41,094 INFO [context] configuration path: E:\code\Prism3\VisionServer\bin\x64\Debug\astra.toml
2018-01-03 10:12:41,094 INFO [context] log file path: astra.log
2018-01-03 10:12:41,094 INFO [context] astra_core library version: v2.0.7-beta-5f803a5e24 API Level: 1
2018-01-03 10:12:41,094 INFO [context] astra_core_api library version: v2.0.7-beta-5f803a5e24 API Level: 1
2018-01-03 10:12:41,094 INFO [context] plugin search paths E:\code\Prism3\VisionServer\bin\x64\Debug\Plugins\;E:\code\Prism3\VisionServer\bin\x64\Debug\
2018-01-03 10:12:41,105 WARN [context] Astra found no plugins. Is there a Plugins folder? Is the working directory correct?
oopsoopsoopsoopsoopsoopsoopsoops2018-01-03 10:12:43,158 INFO [context] client opening streamset: device/sensor0
2018-01-03 10:12:43,164 INFO [astra.streamset] connecting to (1,0) on device/sensor0
Exception thrown: 'Astra.AstraException' in AstraDotNet.dll
An unhandled exception of type 'Astra.AstraException' occurred in AstraDotNet.dll
astra_imagestream_request_modes: Invalid Operation