IOPMAssertionCreateWithDescription needs a timeout. Otherwise deactivating the app will have no effect.

Author: Dominic Rodemer

src/Caffeine/Classes/CAAppDelegate.m

@@ -193,7 +193,7 @@ - (void)timer:(NSTimer*)timer
                                            NULL,
                                            NULL,
                                            NULL,
-                                           0,
+                                           8, //Timeout assertion after 8 sec
                                            NULL,
                                            &sleepAssertionID);
     }