AddThis is no longer running, they have put an annoucement in their website.
“As part of a periodic product portfolio review, Oracle has made the business decision to terminate all AddThis services effective as of May 31, 2023.” https://www.addthis.com/
So the AddThis plugin doesn’t work in OJS. We have delated the plugin in our multi website to avoid confusion.
I am not sure if this is the right way to inform the community or if there have been another post warning about it.
For future references, as Diego explains in gitHub, Shariff is the natural substitute for AddThis.
And while we’re on the subject, it turns out that it’s a much better choice in terms of privacy… so all good news.