The problem is, that heading created with GenerateBlock do not work with the table of contents block.
Changing them to the core heading block does work.
What I noticed is that the GB will no allow an ID to be added to the heading tag, while the core heading block do allow.
That is why the GB headings do not show up in the TOC.
Any ideas how to solve this as I do want to use the GB heading in my articles.
The plugin automatically adds the id to the heading. no need to add them manually. It does so with the core heading blocks but not with the GB heading blocks.
In that case, it’s likely that the plugin is specifically targeting the core Heading block. They would need to check for the Headline block as well or change the way they target elements to look for headings (h1-h6).