Please update Visforms to version 3.6.11. This release has a bugfix für this problem.
Please note: We have made changes to the view files in Visforms 3.6.5. So if you have created overrides for the Visforms view files in your template, you will have to remove those overrides and create new one's based on the new Visforms view files.
If you do not want to update your Visforms installation, but only need a bugfix for the missing rechaptcha you could try to follow the instructions in this forum post.