Inspect for consumer plans only works with Sketch or Photoshop documents synced to prototypes via the Craft Sync plugin. All artboards from your Sketch or Photoshop document will be Inspect-ready. Enterprise users and existing Inspect Public Beta users will be able to continue to use server-side extraction for Sketch documents (via drag and drop method, InVision sync, Dropbox or Box sync, and Craft Sync).
At this time, we limit the amount of time we’ll allow for processing of a file. If a file exceeds that limit, processing will abort. During the Inspect beta phase, we limit the amount of time allowed for processing so you may encounter trouble with more complex files initially.
We'd suggest you try splitting your file into smaller parts if you'd regularly running into trouble during the beta.
A file with no artboards will also fail.
If you still encounter trouble even with simple files, please contact us for help.