Sony's PlayStation 4 Pro currently ships with v3.70 OFW, and if you need yet another reason not to update the PS4 Pro Firmware besides the PS4 Pro 0day Exploit and Scene Dev Alerts according to reports after updating to v4.05 OFW 2160p resolution is unavailable on HDMI 1.4 4K TVs... yet 2160p@YUV420 mode was supported in the stock 3.70 Firmware. 
As expected, this removal has left many without a HDMI 2.0 4K TV quite upset, to quote from PlayStationLifeStyle.net further on the issue:
"First spotted by WCCFTech, the PlayStation Europe forums are littered with complaints regarding the topic, with many finding that the 2160p options are greyed out (read: unsupported) when using HDMI 1.4. Prior to the Pro’s launch, Sony had initially warned users that a premium HDMI cable would be required to fully appreciate the console's two display options: 2160p YUV420 and 2160p RGB.
At the time, Eurogamer reported that “2160p YUV420 is interesting in that this allows PS4 Pro to connect to older 4K screens that lack the full HDMI 2.0 implementation. By reducing chroma information, the required bandwidth drops down in half, allowing HDMI 1.4 screens to get a full 60Hz signal.”
But the reason PS4 Pro owners have taken issue with the lack of support is that, according to WCCFTech, it suddenly became unavailable for those using HDMI 1.4 displays after the launch of firmware 4.05. Sony is yet to release an official response, but those who reached out to PlayStation support reveal that a fix is in the works."
Hopefully most with a PlayStation 4 Pro won't be updating beyond the stock PS4 Firmware here, but for those who did we'll post the fix once Sony releases it... most likely in their next 'improves the quality of the system performance' update.
As expected, this removal has left many without a HDMI 2.0 4K TV quite upset, to quote from PlayStationLifeStyle.net further on the issue:
"First spotted by WCCFTech, the PlayStation Europe forums are littered with complaints regarding the topic, with many finding that the 2160p options are greyed out (read: unsupported) when using HDMI 1.4. Prior to the Pro’s launch, Sony had initially warned users that a premium HDMI cable would be required to fully appreciate the console's two display options: 2160p YUV420 and 2160p RGB.
At the time, Eurogamer reported that “2160p YUV420 is interesting in that this allows PS4 Pro to connect to older 4K screens that lack the full HDMI 2.0 implementation. By reducing chroma information, the required bandwidth drops down in half, allowing HDMI 1.4 screens to get a full 60Hz signal.”
But the reason PS4 Pro owners have taken issue with the lack of support is that, according to WCCFTech, it suddenly became unavailable for those using HDMI 1.4 displays after the launch of firmware 4.05. Sony is yet to release an official response, but those who reached out to PlayStation support reveal that a fix is in the works."
Hopefully most with a PlayStation 4 Pro won't be updating beyond the stock PS4 Firmware here, but for those who did we'll post the fix once Sony releases it... most likely in their next 'improves the quality of the system performance' update.
