Hello Bit, since you are using a Display port to HDMI cable, I would recommend you to test the system using straight connections. So please check if there is an HDMI cable you can try on this NUC.
You can also check if there is a new BIOS version that needs to be installed on your product and the latest graphic drivers.
Please choose the OS you are using and download the latest version. https://downloadcenter.intel.com/SearchResult.aspx?lang=eng&ProductFamily=Graphics&ProductLine=Laptop+graphics+drivers&ProductProduct=4th+Generation+Intel%C2%AE+Core%E2%84%A2+Processors+with+Intel%C2%AE+HD+Graphics+5000&ProdId=3721&LineId=1101&FamilyId=39
I did try a Mini-HDMI to HMDI cable, and it did not interfere with the Sony HDMI Control function, but this type of connection does not have the bandwidth to stream my content properly.
I am using the recently release BIOS for the D54250WYK NUC.
Perhaps I can try a different Mini Display Port to HDMI cable. Is there a recommended cable I should use?
I've seen several different cables available, some are called Passive Adapers, and others are called Active Adapters.
I'm not sure what I should use. Any ideas?
Bitbucket, similar issues were reported about this. I just wanted to let you know that this is still in process, and we are trying to find a resolution. HDMI Audio Loss - Call To Action
In the mean time, you may want to try the latest graphic driver available.
I have my D54250WYKH NUC connected via mHDMI -> HDMI to a Yamaha RX-A1010 and a Samsung UNC60C6300 which works, for the most part, OK. I have issues where the NUC constantly keeps indicating either the Yamaha receiver is in the HD audio entry or the Samsung TV. This plays havoc with the applications I'm trying to run. My Samsung TV will shut off the Yamaha receiver but the receiver will not shut of the TV (this may be by design in my case). I am wondering what Sony TV your driving (4k?) and if you're trying to drive higher than 1920x1080 resolution. I've had my NUC driving a HP ZR30w via the mini display port and that worked beautifully at 2560x1600 with excellent graphics performance (though I didn't test the audio since there's none on my monitor).