I bought 2 different types of SD cards (mini SD and SD from Sandisk) to put in my PRIME 4 and in my PRIME GO… I formatted in ex-fat, and synced by Engine software (the latest version). I putted in the devices (with the latest firmware), and no one of two recognized the SD cards!!! Whyyyyy??? HELP ME!
(Sorry for my english… i hope you can understand me)
Hey, you can try the following until someone gonna reply who really know’s whats going on 
In the formatting menu, check the value for the size of the allocations. Make sure this is set on “Standard” (not any other value) and format type to ex-FAT.
Sounds stupid have you gone to source on prime 4. It wont automatically play from anything you put in it
I tried but still not recognized by Denon equipment 