Google translation: "I'm using version 12.3 I also used it in version 12.0 but Lightroom's CTRL+G Image Stacking command isn't working. I already reinstalled and it does not work in these versions. Does anyone know how to fix?"
I verified it's working in my LR 12.3 / Windows 11. Some first troubleshooting steps:
1. Try resetting LR's preferences:
LR sometimes soils its preferences file, and resetting it can fix all sorts of wonky behavior. That article explains how to restore the old preferences if resetting doesn't help.
2. See if another program is intercepting Ctrl G. Restart your computer in Safe Mode With Networking, which will disable all background utilities. Run LR, select two photos, and type Ctrl G.