Hi @MartynMcD,
Google has changed the maps API use and you need an API key in order for it to work on the published custom domain.
Here’s some more resources on this:
https://developers.google.com/maps/pricing-and-plans/standard-plan-2016-update#for-apps-created-before-june-22-2016
We’re working on allowing people to enter their own API keys directly through Webflow, but no ETA on when this will be available, unfortunately.
One possible solution in the meantime, would be to pickup the maps embed code from your customer’s account to embed in the site using the Embed component - they will likely need to get an API key so keep in mind there may be a charge from Google.
The Webflow team is actively working on a solution for this, but I do not have an ETA yet. This change has been beyond Webflow control and originates from Google. I am sorry for the trouble, I can understand the pain on this.
As soon as there is an update, more information will be posted.