Hi. I've read the manual and MANY posts about people using photo bracketing on the P3. I know I'm supposed to hold down on the shutter button and the choices for HDR, multiple exposures and bracketing will appear. For me it doesn't. I can hold down for 10 seconds and it just takes a picture when I let up. What am I missing?? I have the latest DJI Go and everything is up to date. Using a P3S with an iPhone 6s. Thanks in advance!