Failure to Enter Automatic Sleep

Hello,

About a week ago I noticed that the computer failed going automatically into sleep as configured for over two years. I looked up first on Power Options (Power Plan) and then on hardware configurations on Device Manager, but could not find any configuration change. All as usual. Then I used the command line command powercfg -energy and found the following error in the results:

System Availability Requests:System Required Request
The device or driver has made a request to prevent the system from automatically entering sleep.

Requesting Driver Instance
HDAUDIO\FUNC_01&VEN_1106&DEV_0397&SUBSYS_1043836C&REV_1000\4&4ac9a6c&0&0001

Requesting Driver Device High Definition Audio Device

Glad for believing having found the culprit, I searched all possible settings regarding the original (without accessories) motherboard hardware, presently using updated Microsoft drivers, but failed to find any setting to control entering sleep. I also looked up in the registry using a reference from the quoted log. I found the Audio sub-key with four sub-keys containing many sub-sub-keys, but could not find any clear reference to power control.

How can I reset this configuration to permit again the computer entering sleep after the set time elapses, please?