Hi, since changing auto-hide and restarting haven’t helped, please check whether OMEN Gaming Hub is running:
Press Ctrl + Shift + Esc >> Processes >> look for OMEN Gaming Hub >> right-click it >> End task. Then check the taskbar while your browser is still open.
If OMEN isn’t listed, let me know whether the taskbar also disappears when you open and maximize File Explorer, or only in your browser.