Jon Harvey

+1
We have also seen this issue

Thank you. We have tried clearing all the caches.

What we’ll do is trigger a staging copy of the site, and reactivate the plugin on there – then we’ll drop you a line so you can have a look. With the plugin active it appeared to be preventing crucial forms from showing, so we had to disable it – but apprecaite you then don’t have anything to look at!

Thank you, Jon

Realised this error relates to this variation of the plugin; sorry:
https://www.ads-software.com/support/plugin/woocommerce-sendinblue-newsletter-subscription/

Just by way of an update, this issue went away for us when WP was updated to 5.1.1, so it’s possible stability of either the backend editor, or the API was improved, or it may have been a plugin issue that an update resolved.

It still takes a very long time to appear whilst it loads all the parent pages (700+ pages, 30+ seconds), because it is loading the full data for each, as described above. We’ve made a suggestion on the Github page that this be improved by making requests to the API that only return the required fields. However, this may or may not be possible as the API currently stands.

Hello!

We found the new parent dropdown is being retrieved via JavaScript via the API. If there’s an error generating the pages list on the server (say, due to a broken theme or plugin), or nothing is returned (say, due to the request being blocked), the JavaScript will die and not display the parent option at all.

Also, by default it will only retrieve 100 pages at a time, making subsequent requests. If any of these fail, the JavaScript will die and not display the parent option.

There’s an obscure JavaScript error shown in the web developer tools console, but nothing obvious shown on the frontend to indicate anything has gone wrong!