I have a really weird situation where I have 2 amazon 4K fire sticks, one is connected to an ASUS VP28UQGL 4K monitor and the other to a 4K Samsung TV. Disney+ works fine in 4K on the amazon fire stick on my Samsung tv, and indeed the app on the Samsung TV. However, on my monitor it does not stream 4K, only HD, and it doesnt show 4K as available in the Disney+ app. Other apps such as YouTube, Netflix and Amazon Prime all stream fine at 4K on the Fire Stick connected to the monitor. Both sticks are streaming over WIFI - but I am certain it isn't a WIFI issue as the monitor is sitting right next to the router, and my tv is well away from it. The Disney+ app quality settings is set to Automatic, and the firestick display is set to Automatic, and forcing it to 4K resolution makes no difference. So I am at a complete loss on this - is it maybe something to do with HDMI port difference perhaps between the TV and monitor?