shift + H for HDR Merging is not working.

In the link below, from 2017 (no idea if MAC or WIN) it was CTRL + H when selecting the images to bring up the Merge HDR without clicking on the button to Merge HDR. If you wanted to select the images and then select the button to Merge HDR, then holding down shift would do the same thing. See tip 6 in the following:

https://improvephotography.com/49762/create-hdr-lightroom-classic-illustrated-guide/

I believe the KBSC is actually [Ctrl]+[ H ].