In some application icon on store windows disappear, only gray background are shown (as shown in this link: https://drive.google.com/open?id=0B4oRSWSS0hKDOVZNNjhRNlR1LUk) Whereas once downloaded and installed, the start screen wide screen (310x150) and other icons can be displayed in windows 8.1. Icon that I use: https://drive.google.com/open?id=0B4oRSWSS0hKDNlNaQ290b3RmTE0
How to handle it?
I also had a problem where inside Windows Store, empty gray logo was displayed instead of the one I set inside App Manifest as a wide logo. Gray logo was only visible inside the Store, but once downloaded and pinned to the start, wide logo was displayed without problems. I also noticed problems were only inside Store on Surface 1, but not on PCs and Surface 3.
The solutions seems to be to set images for all scales. So open Package.appxmanifest > Visual Assets > Wide 310x150 Logo and under Scaled Assets, set all four sizes. Then you have to create new App Package and update your submission with it on Windows Dev Center.
Hopefully this works for you as well.