Additional Info:
On this post, Chris says:
“Conditional logic can’t make a field required or not, but, you can make that dependent field required, and show or hide is based on the other field. If it remains hidden, even though it is required, the form can be submitted without error. When it is shown, because it is required, it must be completed before the form can be submitted. This is the normal usage for conditional logic (show/hide a field when necessary based on another choice.) If you need more help configuring that, please let us know.” – which I know to be true in previous versions.
In fact, I use this on several different sites successfully. This is why I’m thinking it might be related to the latest version.