It may have something to do with the User Role Editor plugin that I have installed also, although I am not sure of that, since deactivating that plugin does not make the problem go away.
The only way I can make it work now is to give the user who has ‘Author’ access an extra secondary role ‘Editor’. Then they have all the SEOPress boxes, both in the block editor and the original WP text editor.
But that’s not such a good option, because then they can also edit other’s pages and posts. It would be nice if it would function without this workaround.
Any ideas why? I tried many different things before posting to you, but to no avail…