Doesn't Save Form Changes

I’ve tried everything. Deactivated ALL my plugins except this one, and changed themes to either of the latest WP themes, and it still does the same thing .. I can go thru the form, Manage Form and make all the changes, it looks great, but the page doesn’t reflect any of those changes, and when I go back to Manage Forms again, the changes don’t show up.

I’ve seen a number of people comment on this issue, and all I’ve seen (bar one comment in the “Reviews” section” just says “it must be a conflict, deactivate plugins and change your theme” .. neither of which worked. THere’s a comment in the “reviews” section about modifying a file, which I also did, and that didn’t resolve the bug either.

If the developer can offer some assistance it’d be most appreciated. Otherwise, the plugin is great.

Thanks

https://ww.wp.xz.cn/plugins/custom-contact-forms/