Not working with Fusion Builder

Hi @lausianne,

I am sorry that you are having trouble with the plugin. I looked up Fusion Builder and it appears to be a completely custom page building plugin. Toggle wpautop will only work for the default WordPress editing experience.

Hi Jonathan,
Thanks for your reply. The page builder is custom, yes. The editor inside the custom blocks looks like vanilla TinyMCE, plus 1 or 2 buttons.
Meanwhile I tried a few solutions, and what eventually worked for me was this:
https://designmecreative.com/stop-wordpress-from-removing-non-breaking-spaces/
It does not switch off cleanup completely, unfortunately, but at least I can add nonbreaking spaces now.