DP to HDMI connection problems for audio signal

We got a new computer to connect to our TV monitor.
Our computer serves our home as a HTPC (Home Theater PC) Media Server. We leave it on 24/7.
The new computer only had a DP (Display Port) socket to connect to the HDMI socket on the TV.
Consequently, I ordered a cable with a DP plug on one end and a HDMI plug on the other.
There is a built-in adapter on the cable to change the protocols required to convert a DP signal to a HDMI signal.

For an hour or two the new cable worked perfectly.
I watched a couple of shows and left the HTPC alone for a couple of hours.
When I returned to the HTPC, there was no sound. I noticed that the speaker icon in the taskbar on the bottom right of the screen had a red cross. When I hovered my mouse cursor over the cross, there was a pop-up display message that said “No Audio Output Device is enabled”.
After rebooting the HTPC, the audio started working again.
When I went into the Device Manager I noticed a new entry at the top of the list called “Audio Inputs and Outputs”. Under the heading it said “SMART TV (Intel Display Audio) Audio Endpoint so I suspect that the firmware in the converter calls upon the Intel audio driver to be installed.
The next day the same thing happened when I awoke. This time when I went into the Device Manager, strangely the new entry had disappeared which explained the loss of audio.
There was no way to resolve this problem because the new entry contained no power management tab or sleep mode settings.
I then noticed a different type of DP to HDMI adapter and ordered it.|
After connecting this we have not lost the audio at all.
There is a different type of driver being used for this new adaptor as there is no entry in the Device Manager there is only the drivers for the Realtek sound card showing.
Suspecting a bad driver I uninstalled the driver and reinstalled it but it made no difference.
I could not contact the manufacturer of the cable to see if they had a new firmware.
I tried a generic driver but that also didn’t work. So it seems there is an incompatility between the Intel audio driver and the convert’s firmware.
The only resolution was to buy the new converter cable.

HDMI plug on the left and Display Port plug on the right

New entry at top of the Device Manager. Uninstalling the driver made no difference.

Cable that caused loss of sound
Transformer that worked