Forced double opt-in issue

I’ve been testing the latest version of the plugin on several sites, and the latest version seems to be forcing double opt-in.

One site previously had version 0.9.27 and immediate subscription worked without issue. The latest version(s) now has drop downs for subscribing if the opt-in checkbox is ticked, and another for double opt-in (subscribing only once confirmed through a confirmation email).

Despite the latter being set to single opt-in, the subscription is now set to send a confirmation email, and the subscriber is added only once they confirm through that email. The audience on the Mailchimp side is also set to be single opt-in, so settings-wise, everything should be correct. And this seems to happen once after saving/updating a form, which means the plugin must be saving some kind of options row in the database that causes this.

I tested on another site with the following sequence:
– Updated from 0.9.27 to 0.9.71
– Tested subscription, worked fine as immediate single opt-in.
– Edited the form and hit save. No setting changed.
– Tested subscription again, and now forces double opt-in.

I think there must be some code that triggers on the WordPress save hook which might need reviewing, unless I’m missing something.