Yesterday I upgraded to Windows 10 mobile on my MS 640 XL dual and I was very pleased with the results and UI UNTIL I tried a video recording (with MS Camera, of course). The video was fine but there was no sound recorded at all. I have gone back to 8.1 and I can use Lumia Camera without any sound or video problems. I noticed also when on Windows 10 mobile that "Mini Recorder", a neat little audio recorder, wouldn\’t work at all. (I have Windows 10 mobile running on my Lumia 925 and audio recording is OK when recording videos.) Any good advice about the MS 640 XL audio recording from knowledgeable folk welcome.