camera shutter sound disappeared, then returned

[ribjig]

P4P+
used only to take photos;
always set on f4.5 & ISO 100;
always check focus by touching screen
& getting double beep sound confirmation;
always touch screen virtual button & hear
pseudo shutter "sliding" sound;
BUT THIS MORNING...
there was no shutter sound on several button presses
(there was focus confirmation sound)
so landed, turned RC & P4P+ off, turned both back on,
changed camera to video & back to camera again,
took grounded photo, voila, shutter sounded...
flew up to take aerials, all worked...

CAN ANYONE MAKE EDUCATED GUESS AS TO
WHY SHUTTER SOUND TEMPORARILY DISAPPEARED?
WOULD THERE BE WAY TO MAKE IT RETURN IN FUTURE
WITHOUT LANDING & REBOOTING? thanks in advance

 

[JeffreyS]

I believe that if the unit is still writing the file to the card, there will be no sound and the picture will still be recorded. But look at a the little camera icon, it should have an animated circle around it indicating file being saved..