Hi George,
The problem occurs on every category page.
I switched the theme and the problem was still there. We did reboot the server last night and have been deleted past events and media to free up disk space.
On our Dev sever, I cannot replicate the problem. They are 100% duplicates of each other and live on the same server. Some content is different but I don’t think that is impacting it.
The only code I changed most-recently was in my header file that called thumbnails. I added !is_singular( ‘tribe_events’ ) to omit thumbnails – but that was it.