OK. Understood. I am also getting some other odd behaviour even with 4.22.5 installed so that may be it. I have updated back to 4.24. To be clear, we only noticed the results differences the day we updated to 4.24, but it is possible it was ocurring before.
I have exported the public instance. I also have a second instance which is substituted for logged in users which should be identical except for additional members’ content. But other result differences have appeared.
Thank you and I’m sorry about the restircted access.