If the wallet is fully locked, clicking [New Address] gives a message that the wallet needs to be unlocked in order to create a new address.
If the wallet is unlocked, clicking [New Address] will add a new address to the list, in the Addresses tab of the GUI.
With the wallet unlocked for staking only, clicking [New Address] brought up a dialog box and an error message that it needs to be unlocked, but clicking [OK] added an entry to My Addresses, without an address in it.
Next, I locked the wallet, and clicked [New Address] again and it filled an address into the slot that had no address in it! AND the front (bottom left) of the wallet place where the original "receiving address" normally is copied from changed to just "..." and clicking the copy icon copied nothing or null.
Clicking [New Address] again, while locked, did the original correct thing, of not bringing up a dialog box, but giving "Wallet locked, please unlock it to continue."
Unlocking now and clicking [New Address] again, correctly generated another address, but did not fix the originally displayed receiving address from the front of the wallet.