Everything was working great up until a few months ago, and suddenly stopped. What gives?

1. Make sure you have your API key loaded inside your functions file (this is the code for ACF Pro):

function my_acf_init() {
    acf_update_setting('google_api_key', 'your-key-goes-here');

add_action('acf/init', 'my_acf_init');

2. Make sure your API key is set up with a credit card.

3. (This is the one that eluded me for several hours.) You’re going to want to enable “Places API for Web” — otherwise, the dropdown won’t work. You can activate that inside your Google Cloud Platform Console (https://console.cloud.google.com/google/maps-apis/overview?), inside the settings for whichever API you want to use (you can choose inside the dropdown):

Enabled APIs Screenshot