If the laptop works in 2D mode, to conserve battery apparatus is switched to the built-in CPU graphics with built-in CPU logic disables the discrete graphics card from the bus (architecture IBM PC allows only one video card at any one time), and it is natural that in this case no diagnostic tools can not interrogate her, and the user has a feeling of its invisibility.
The way how HWiNFO handles such GPUs is intentional - NVIDIA Optimus technology, which is responsible for disabling the DGPU when not used is designed to reduce power usage.
And thus HWiNFO doesn't make any changes to this behavior - it doesn't change the state of the GPU. It should just recognize it, but all other parameters are not available, because the GPU is physically switched off. Once you put some load on the DGPU, Optimus will enable it and HWiNFO should immediately recognize this and start providing all parameters.
If you still prefer to see all DGPU parameters and don't care about preserving power, you can enable the "Poll Sleeping GPUs" option in HWiNFO. In this case, HWiNFO will wake the DGPU up in each cycle to read parameters.