Just had that issue with MacBook Pro's and the LG UltraFine 4K Display from the Apple online store. It appears that brand new MacBook Pro's don't seem to output at 4K which was a bit of a shame.
In theory, yes. With the three MacBook Pro's and LG Ultrafine 4K displays we bought, unfortunately the MacBook Pro's either don't recognise them as having that display resolution, or they can't output at that display resolution. They still look great. Just not 4k.
Just had that issue with MacBook Pro's and the LG UltraFine 4K Display from the Apple online store. It appears that brand new MacBook Pro's don't seem to output at 4K which was a bit of a shame.