We just pushed up a form with reCaptcha version 2 so that users don't have to pick images. The behavior is inconsistent; some users on mac / chrome don't see the images but the same user on safari mac is forced to pick images.
A user on windows / chrome is forced to pick the images. We can't really determine why some users are seeing images while others are not. Per the instructions we have, it should just be the site id being associated to a version 2 account that is set as checkbox only.
For reference, here is the page.