Losing Conditional Rule when saving form

For the new forms the condional fields works fine but oldest one (created before installing condional Fields plugin) lose the condional rule after saving the form.
In other hand, when i activate the Conditional Fields plugin, all forms can’t send email (error message display in frontend for users)

does it work if you switch the conditions to text view and then save the form?

No for the oldest ones @jules-colle, neither by Conditional rule forms neither by text one’s but what’s strange all forms builded by Contact form 7 plugin don’t send email and if i desactivate Condtional Fiels plugin, forms and sending mail remain work.

Sounds like an interesting bug..

Do you think it’s possible to recreate this on a fresh WP install?

Let’s say you take these steps:
– install WP and CF7
– Create a CF7 form
– Install Conditional Fields for CF7
– Add some conditions to the original form and save it
– Check if the conditions are still there

Do you think the conditions will work in this case? Would be great if someone could verify this.

The reason I ask, is because I never heard this kind of bug reported, so I would be amazed if the above steps will cause the conditions to indeed disappear. Given that this seems like a very common use case.