Not sure if you found a fix for this but something that may help narrow it down…
Using an incognito/inprivate browser window, pull up the developer tools using F12 and make sure you are on the ‘Console’ tab. Try using your autocomplete field as you have been and see if any errors pop up.
I just set this up for the first time and discovered I needed to add the Maps JS API as well, using those developer tools.
Hope that helps!
Have you tried using the developer tools in your browser to see what’s going on?
FYI I just set it up for the first time, followed the instructions but couldn’t get it to work properly. In the end I needed to configure the API key for both the “Maps JavaScript” API, as well as the “Places” API.
I did modify the back-end php file to use the correct URL for places specifically but then had CORS issues, so just keep that in mind as well.
Hope that helps!