"Upload failed" or the analysis never completes
Usually encoding, size, or a stale browser session.
Try: 1. Re-saving the CSV as UTF-8 with LF line endings. 2. Splitting files over 20 MB into two uploads. 3. Signing out and back in to refresh your session. 4. Opening a private window to rule out an extension.
If the analysis reaches "processing" but never finishes, contact support with the analysis id — we can inspect the run.