Hi Sytze,
Hope you solved this issue, already, though I am still interested what the solution was
What version of Mendix are you using? Did you update the Google maps widget after the merge?
Did you check your project directory /widget folder, there could be multiple versions there.
In that case, remove the both and update the latest from the app store.
Issues with custom widgets can best reported via GitHub to notify the developers. In this case: https://github.com/mendixlabs/google-maps/issues
Cheers,
Andries