Documentation
Start with the thing Capper can verify.
Most problems are a permission, model-server, secure-input, or license-state issue.
Accessibility looks enabled, but Capper disagrees
Open System Settings → Privacy & Security → Accessibility. Remove the stale Capper entry, add the exact app you now use, and enable it again. A rebuilt or newly signed copy can have a different macOS identity.
The Local model is unreachable
Confirm the model host is open, its API server is running, and a chat model is advertised. Return to Capper Settings, select the matching preset, and choose Refresh Models or Apply & Refresh after editing a custom URL.
The global trigger does nothing
Check Accessibility first. If another app has enabled Secure Event Input, use the menu-bar fallback and try again after leaving that secure field. You can also switch to Option–Space in Settings.
The license cannot be replaced
Capper requires explicit deactivation before another key can be entered. Use Deactivate This Mac and allow its retryable cleanup to finish. This protects the Polar activation slot from being orphaned.