I believe, that is your default Windows 11 Start panel. Please open up Start11. Just type "Start11" when you have that Win11 start panel open. Open Start11 configuration windows. Look at the "Use the Start11 Start Menu" slider button is "on" or "off"? Refer screenshot below.

If its "off", turn it "on". Retest and report back. But, if it actually already "on"
Open up Control Tab and check if it is set correctly to open up Start11 menu on both the mouse on Start button and the keyboard win key. Report back.

Thank you,
Basj,
Stardock Community Assistant