Actually, follow-up question:
Where are you running appleseed.studio from?
Developer builds contain a
sandbox/ directory containing a complete deployment of appleseed with all its support files. Binaries are automatically copied to
sandbox/bin/ by the build system.
This is where you’re supposed to run appleseed from, if you built it from source. Running appleseed from
build/ is unlikely to work, and if it does, it’s by accident.