My iPhone 4 used to repeat the alert if not read. I recently changed it to repeat 10 times and now it alerts once and never again. I have reset back to two alerts and it still only sounds one. Any ideas.
Close down all background apps (double tap the home button and delete all the icons along the bottom) and then do a hard reset (home button and power button held down for 10 seconds)...and see how that goes. This has been a previously documented issue although not sure the exact cause was ever found.
Artificial intelligence is no match, for natural stupidity!