It didn’t start til I activated Relevannsi as far as I can tell. The trouble is we need the plugin or we get no search results. We are also using Staff List Pro, and without Relevannsi all the content from that is ignored in search results.
The odd thing though is I have used Relevannsi with GeneratePress several times before and it never caused this. (I’ve contacted them too just in case).
But it seems to be something about Relevannsi, Generatepress and the Staff List Pro that is clashing. 🙁 And the if Staff List is the root they are the least responsive in support and very critical part of site!